Compressed Air for Packaging Machines

Compressed Air for Packaging Machines

Controlled purpose: relate cycle sequence, blow off and actuators to machine demand. Required asset: Packaging Cycle Air Balance. Authoring completion does not establish acceptance of an installed machine or authorise production publication.

1 How to establish packaging machine air demand

Compressed air demand for a packaging machine should be established from a time-aligned record of machine states, airflow, pressure and product counts. Integrate flow on a declared reference basis over complete cycles and a representative production interval. Include actuator movements, blow-off, purge, standby demand and rejected attempts within the stated boundary. Verify dynamic pressure at the machine while other permitted loads operate. Acceptance must identify the product, speed and rejected-cycle treatment.

A machine can consume little air over a shift yet need a substantial short pulse during a clamp, transfer or clearing operation. Conversely, a modest continuous purge can account for much of its daily consumption. A single average flow or an inlet connection size cannot describe both behaviours. The useful engineering output is a Packaging Cycle Air Balance that connects the quantity consumed to the event that consumed it and to the quality of the resulting product.

It does not prescribe a compressor size from packs per minute, select a universal operating pressure, or establish product-contact air quality for every packaging process. Their utility demands enter this balance only where the defined packaging-machine boundary actually includes them.

2 Name the product and define a cycle

Identify the product or stock-keeping unit, pack size, material, format tooling, recipe revision and machine configuration. State whether the machine fills, seals, wraps, labels, erects, closes, collates or transfers the pack. These functions create different air events. A label change that leaves the pneumatic sequence unchanged may be immaterial; a new pack requiring an extra clamp, air blast or reject action can change the balance.

Define the start and end of one cycle from an observable control event. An index-to-index interval may be suitable for an indexing machine; a continuous machine may need a repeat period covering all relevant stations. Specify whether a cycle produces one pack, several packs, a case of packs or no saleable unit during setup. Keep cycles, attempted products, completed products and accepted products as separate counters. A cycle counter is not automatically a product counter.

Record the commanded speed and the achieved operating rate. Also report accepted output over elapsed time, including the stop policy used in that interval. A machine set to 30 cycles/min can produce fewer than 30 accepted packs/min because of rejects or interruptions. This distinction is essential when comparing recipes, improvements or machine quotations. Do not use theoretical productivity as measured output.

3 Draw the air boundary before calculating

Place the primary balance boundary at a named machine inlet, with the meter position shown relative to the isolation valve, local receiver, filters, regulator and valve island. Mark every supply crossing the boundary. A second pneumatic connection, an independently fed reject station or a vacuum ejector supply can otherwise disappear from the total. Identify downstream users that belong to another machine and exclude or separately measure them.

The boundary determines which treatment losses and purge flows belong in the result. A machine inlet meter downstream of a central dryer does not measure that dryer's regeneration demand. An onboard dryer supplied downstream of the meter does. Report machine demand and upstream supply-system demand separately, then consolidate them once at the plant boundary. Pressure drop is a condition of delivery; it is not an additional volume of consumed air to add to the ledger.

Storage requires an explicit inventory check. If a receiver or manifold ends the test at a different pressure or temperature, incoming air and consumed air need not be equal. Use equivalent initial and final inventory or calculate the inventory change with stated assumptions. A short test ending with a depleted receiver can understate the sustained inlet requirement. Avoid taking a convenient interval that starts fully charged and ends just before recharge.

4 Describe operating states and transitions

Use the machine's actual state names where available and map them to the balance. Production, blocked, starved, ready, standby, changeover, stopped, isolated and restarting are not interchangeable. For example, a starved machine may continue a protective purge while an isolated machine cannot. The table is a classification aid; the installed controls determine the permissible actions.

Transitions can govern supply even when steady production is satisfactory. Restart can charge several manifolds simultaneously; recovery after a blocked discharge may briefly align machines that normally run out of phase. Include permitted manual and recovery modes in the sequencing review. Do not create unsafe fault conditions merely to obtain a trace. The site and machine supplier must approve the test method and protective behaviour.

5 Define reference flow and pressure precisely

Reference flow expresses the mass flow as an equivalent volume at stated pressure, temperature and moisture conditions. They are not additional unit standards. Labels such as normal litres, standard cubic feet or free air are incomplete for comparison unless their exact reference conventions are known.

Actual line flow is the volume passing at the local compressed condition. For the same dry-gas mass, a lower absolute pressure corresponds to a larger volume. Do not compare actual line litres with reference litres, or convert a reference-flow meter a second time as though it measured actual line volume. Obtain the meter configuration and the supplier's rating basis before combining numbers.

Use bar(a) for absolute pressure and bar(g) for gauge pressure. Absolute pressure equals gauge pressure plus the applicable atmospheric pressure. Temperatures in gas calculations must be kelvin. A pressure requirement must name its measurement location and operating state: machine inlet during the governing event, valve-island feed during actuation, or another agreed interface. Static pressure before a cycle cannot demonstrate pressure while the cylinder fills.

For compatible composition and moisture basis, the gas relationship is V_ref = V_actual × (p_abs/p_ref) × (T_ref/T_actual) × (Z_ref/Z_actual), where Z is compressibility factor. The ideal-gas screen sets the Z ratio to one and states that approximation. If moisture bases differ, reconcile dry-air partial pressure or use an appropriate mass-flow conversion; changing only total pressure and temperature does not resolve the mismatch. [C1]

6 Translate cylinder movements into reference air

For a conventional single-rod double-acting cylinder, the cap-end swept volume is A_cap × stroke and the rod-end swept volume is A_annulus × stroke. A_cap = πD²/4; A_annulus = π(D² − d²)/4, with bore D and rod diameter d in compatible units. One extension and one retraction fill different volumes. Counting two full-bore strokes overstates the rod-side swept volume.

A preliminary consumption model converts each filled swept volume at its assumed chamber pressure and temperature to reference air, then sums the events. This requires adequate filling and a defined exhaust condition. Chamber pressure during motion can differ from the regulator indication. Partial strokes, cushioning, retained pressure, pressure-saving circuits and regeneration can invalidate a simple full-stroke model. Festo's published consumption example accounts for rod displacement and explicitly qualifies the result as approximate. Its product-specific values are not adopted here. [P1]

Cylinder geometry estimates air quantity; it does not establish force, permitted speed or successful motion. Force depends on the opposing chamber pressure as well as the driven area, with friction, load and dynamic effects also relevant. A geometrically plausible air budget cannot prove that a clamp holds the product or that a slide reaches its sensor before the next step.

For spring-return, rodless, rotary or multi-position devices, use the actual pneumatic arrangement and applicable consumption data. Count only the powered movements that occur, plus separately identified accessories. Preserve whether a supplier quantity means one stroke, a double stroke, one switching event or a complete machine cycle. Record how many such events occur per packaging cycle.

7 Account for valves and connecting volumes once

Treat air through a directional valve into a cylinder as the cylinder's supply stream. A valve's rated flow capacity is not its continuous consumption, and it must not be added to cylinder demand as another load. Add only distinct pilot consumption, specified bleed, vented control volumes or other actual branches that the chosen boundary excludes from the cylinder figure.

Tubes and dead volumes can add repeated charge demand. For a fixed volume vented to residual absolute pressure p_low and recharged to p_high at the same assumed temperature, the ideal reference increment is V_dead × (p_high − p_low)/p_ref × T_ref/T_dead. This differs from the swept-volume term because the fixed space already contains residual gas before recharge. Identify which spaces actually vent at each switching event.

Permanent supply manifold volume generally fills at startup and then supports changing inventory; it is not automatically fully recharged from atmosphere every cycle. A measured machine-inlet trace already includes the refill captured by that meter. Do not add a cylinder estimate, a hose allowance and the measured inlet total together. Keep the measured total as the primary result and the component model as a reconciliation model, with discrepancies investigated rather than hidden inside a generic margin.

8 Measure blow-off duration and useful duty

Blow-off demand is the integral of actual supply flow while the jet operates. A rectangular approximation uses q_on × t_on/60 when q_on is in L_ref/min and t_on is in seconds. Use that only when flow during the window is reasonably represented by q_on. Include valve delay, opening behaviour, residual tail flow and repeated commands when they materially affect the quantity.

The useful treatment window may be shorter than the commanded window. Compare product presence and the required removal or positioning result with actual air-on time. A jet operating between packs consumes air without necessarily contributing to accepted production. Conversely, shortening the window until consumption falls can increase rejects, rework or downstream jams. Compare total air per accepted product while holding the agreed product outcome constant.

Retain that distinction here: a jet's total discharged or induced flow is not necessarily compressor-supplied flow.

9 Keep purge and vacuum demand visible

Purge can protect an optical sensor, prevent contamination ingress or serve another documented function. Identify the purpose, required condition, control logic and authority for changing it. A continuous purge remains in the balance during every state in which it actually operates. Do not describe all nonproductive flow as avoidable leakage or assume it can be shut off whenever product movement stops.

Where vacuum ejectors are fitted, account for their compressed-air motive supply, vacuum generation and release-blow windows. Vacuum flow at the suction port is a different stream from compressed-air consumption at the ejector inlet. A vacuum switch may stop motive air during a satisfactory hold, while porous packaging can cause repeated evacuation. Use the observed control sequence and workpiece condition rather than assuming continuous or perfectly intermittent operation.

Keep the product-contact assessment separate from pneumatic reliability. Air used to clear an exposed pack or contact a product may require different evidence from air confined to an actuator. Identify direct contact, possible indirect contact and exhaust routes near the product. The responsible product-quality function defines the applicable acceptance limits; the presence of a filter or a compressor technology label does not establish hygienic suitability.

10 Distinguish idle demand from leakage

Measure ready, standby and isolated conditions separately, with pressure and connected equipment recorded. Ready-state flow can include deliberate purge, valve bleed, ejector demand and leaks. Only a verified allocation can identify the avoidable part. Changing state can also change pressure, so a lower reading after isolation or regulation is not a direct leak comparison unless the conditions are understood.

Investigate continuous demand with an approved leak survey and controlled sectional checks. Record the location, pressure, operating state, method, evidence and repair disposition. A branch that cannot be isolated safely remains an unresolved allocation; do not disconnect it for convenience. Repeat the relevant measurement after a repair and retain the baseline so apparent improvement can be separated from a changed recipe or pressure.

The DOE sourcebook supports identifying leaks and examining their relationship to system controls. It does not establish a universal leakage allowance or a guaranteed electrical saving for this machine. Report reference-air reduction first. Demonstrating an energy reduction requires a defined compressor-system boundary and measured or justified control response. [P2]

11 Combine concurrent machines using time

Represent each machine as q_i(t) on the same reference basis and time axis. The common-header load is the sum of separate streams at each instant, with shared loads added once. Average demand over a representative interval helps assess air quantity; the time history reveals overlapping peaks and recharge requirements. Do not substitute an unexplained diversity factor for sequence evidence.

A timing offset can reduce a common peak without reducing total air. Check whether the offset is enforced, remains effective after a stop and survives a speed change. Two free-running machines at slightly different rates can periodically align even if a brief observation shows staggered events. Assess the worst permitted phase relationship or support a different design basis with controller logic and recorded operation.

Evaluate line dependencies before changing timing. Delaying an air event can interfere with transfer, seal dwell, accumulation or a safe state. The machine integrator owns the acceptable sequence. Air-supply planning should document feasible alternatives and their evidence, not silently change production logic to make a smaller supply appear adequate.

12 Check treatment and point-of-use restrictions

Trace the complete delivery path: central treatment, distribution, branch pipe, isolation valve, couplings, hose, local treatment, regulator and machine passages. Record the installed identities and relevant pressure-flow characteristics. Nominal connection size alone does not establish bore or transient delivery. A replacement quick coupling or long temporary hose can alter the available pressure during an otherwise unchanged cycle.

The DOE sourcebook identifies end-use components as possible pressure-drop sources and recommends measurements at different points to locate restrictions. Apply that principle with simultaneous readings across the actual packaging branch. Do not copy its illustrative pressure numbers into the acceptance specification. [P2]

Select and maintain treatment against documented quality and delivered-duty requirements. A filter can satisfy a filtration function while becoming a flow restriction; an oversized contamination claim cannot compensate for poor dynamic pressure. Conversely, bypassing required treatment to restore pressure does not establish an acceptable installation. Compare component condition, rated operating conditions and pressure behaviour while retaining the required quality function.

Do not add lubricators by default. Establish whether the installed components require, tolerate or prohibit lubrication and whether lubricant could reach sensitive product areas. Quality sampling must identify the location and operating condition represented. A clean sample upstream of a contaminated hose does not demonstrate quality at the point where air reaches the product.

13 Verify dynamic pressure and recovery

Log pressure at the machine inlet and at the critical downstream interface where practical and authorised. Use instruments and a recording system able to resolve the relevant transient. Long sensing tubes, damping and display averaging can conceal the dip that causes a delayed stroke. Retain sensor response information alongside the logger sampling interval; a fast logger cannot recover a transient removed by a slow sensor.

Time-align pressure with flow, valve commands, position confirmation, faults and reject signals. A dip coincident with a clamp event is a useful hypothesis, but timing alone does not prove the root cause. If inlet pressure stays stable while valve-island pressure falls, investigate the intervening path. If both fall while several machines recharge, examine common supply and sequencing. Stable recorded pressure with poor motion also warrants mechanical and exhaust-path checks.

Acceptance should define the permissible pressure envelope, location, duration treatment and recovery requirement from applicable machine evidence. No universal minimum, dip duration or margin is provided here. Record how measurement uncertainty is handled near a limit. An observed value barely above a threshold does not establish an unqualified pass when the decision rule and uncertainty have not been agreed.

14 Use local storage as an inventory problem

Local storage can supply part of a short event and recharge between events, but it does not create sustained air capacity. Usable inventory depends on initial pressure, minimum usable pressure, gas temperature, connected volume and flow restrictions. A vessel volume alone cannot establish pressure at a rapidly filling cylinder.

For an isothermal ideal-gas screen, usable reference volume is V_receiver × (p_start − p_end)/p_ref × T_ref/T_receiver. Pressures in the inventory calculation are absolute, although their difference has the same numerical value on a consistent gauge basis. The model is a preliminary inventory relationship, not a receiver design method. Rapid discharge temperature change and connecting losses require further assessment.

Place storage relative to the limiting restriction deliberately. A receiver upstream of a restrictive regulator may not resolve the downstream event. A receiver downstream changes stored-energy, isolation and restart considerations. Machine and utility specialists must approve the configuration and its protection. Include recharge in the repeated cycle and test enough repetitions to reveal progressive depletion.

15 Plan a measurement that can answer the decision

Write the measurement objective before choosing instruments. A batch air-per-product comparison needs trustworthy integrated volume and aligned product counts. A valve-island pressure investigation needs dynamic pressure and event timing. A plant capacity assessment also needs simultaneous users and supply behaviour. One temporary meter may support the first objective without resolving the others.

Record meter identity, range, uncertainty statement, calibration status, reporting basis, installation requirements and the actual installation. Check turndown and zero behaviour during standby as well as maximum flow during pulses. Select a meter appropriate to the gas condition and duty. Saturated or clipped peaks understate demand; a low-flow reading below the credible range cannot establish a precise leakage quantity.

Use the shortest material event to justify acquisition response. Demonstrate that the chosen instrument and time resolution capture its area and timing adequately, for example by comparison with a faster validated acquisition or an independent totaliser over repeat events. There is no universal sampling interval for every packaging machine. Retain any unresolved aliasing or response limitation in the disposition.

Synchronise clocks and event counters. Define how timestamp offsets are determined, how products crossing the window boundary are handled, and how buffered output is matched to air consumed upstream. For a long line, the accepted product may emerge later than the corresponding pneumatic action. Correct that association or use a closed accounting interval with documented starting and ending work in progress.

16 Retain raw data and separate observation from inference

Preserve the raw trace, original units, timestamp convention, instrument configuration, recipe, controller export and product-count evidence. Store processed values separately with the transformation method and revision. Keep missing samples visible. Filling a gap with an assumed constant can support an explicitly qualified estimate, but it must not become an unmarked measured result.

A representative trace includes variation. Capture enough cycles and relevant states to support the intended conclusion, including permitted starts, rejects, short stops and simultaneous users. Document why the duration is representative. A single attractive cycle is useful for explanation but cannot establish a production-wide acceptance result. Show distributions or ranges where cycle variability matters rather than reporting only one mean.

Use a reconciliation interval with known initial and final inventory. Compare integrated inlet air against component events and background demand. Differences can arise from unrecorded purge, retry actions, incorrect valve-event definitions, meter basis, leakage or storage change. Do not force agreement by adding a percentage until the balance appears complete. Record the residual, credible uncertainty and the next check that would resolve it.

17 Calculate air per cycle and accepted product

For a reference-flow trace, V_in,ref = ∫q_ref(t)dt. If q is in L_ref/min and t is in seconds, divide the time integral by 60. For interval-average samples, sum q_j × Δt_j/60. For instantaneous samples representing a continuous trace, a justified trapezoidal integration uses (q[j] + q[j+1])/2 × Δt[j]/60. Preserve the distinction: a time-interval average is already averaged and should not automatically be trapezoid-averaged again.

Consumed volume inside the boundary equals inlet volume plus other incoming streams, minus outgoing transfer streams, minus the increase in stored inventory, all on the same reference basis. In the common single-inlet case with no transfer and equal start/end inventory, consumed volume equals integrated inlet volume. State whether the reported metric is purchased inlet air or inventory-corrected consumed air; do not switch definitions between baseline and trial.

Air per cycle = V_ref/N_cycles. Air per attempted product = V_ref/N_attempted. Air per accepted product = V_ref/N_accepted. Each ratio requires a positive denominator and a matching accounting window. If there are zero accepted products, report the consumed air and zero output; the accepted-product ratio is undefined. Displaying zero would falsely reward a failed run.

Average production flow for a stable repeated cycle is V_cycle × cycles/min. For batch accounting, divide batch volume by elapsed minutes. Neither expression establishes the highest short-duration flow. Retain the trace or a peak statistic with its averaging window and instrument response whenever capacity or dynamic delivery is assessed.

18 Keep rejected cycles and rework in the numerator

Air consumed by rejected or repeated attempts remains part of the resource used to obtain accepted output within the chosen scope. Report reject counts and causes separately so an improved ratio is not mistaken for reduced pneumatic consumption when it actually reflects better yield. Conversely, a shorter blow that reduces air per command can worsen air per accepted product if rejection rises enough.

Define rework rules before the test. Count a physical product accepted after two passes once in unique accepted output, while retaining both passes' air. If rework occurs outside the meter boundary or reporting window, either include its measured consumption through a reconciled record or label the result as excluding that rework. Do not silently count a first-pass reject again as a new accepted product and also retain the original attempted count without explaining the relation.

For multi-up tooling, record occupied positions, empty pockets and product count per cycle. A partially filled cycle can use most of the normal air while producing fewer units. Report package, case, bottle or other product unit explicitly. Ratios per case and per individual pack are different metrics, even when the machine handles both.

19 Worked case A Reference air from a cycle trace

Hypothetical worked example only. The following interval-average trace represents fictional measurements of a single-pack indexing cycle. It is not an OEM rating, actual production record or operating recommendation. Assume dry reference air at 1.000 bar(a) and 293.15 K, interval-average reporting, complete 2.00 s cycles, one attempted pack per cycle, and equal gas inventory at each cycle boundary. All downstream machine branches are inside the inlet meter boundary.

Method: V_cycle = (360 × 0.30 + 180 × 0.50 + 600 × 0.20 + 120 × 0.40 + 30 × 0.60)/60 = 6.40 L_ref/cycle. The repeated-cycle rate is 60/2 = 30 cycles/min. Average flow is 6.40 × 30 = 192 L_ref/min. The 600 L_ref/min row is an interval average, not proof of the instantaneous peak.

Assume a fictional 10 min run contains 300 such cycles, including 12 rejected packs whose measured traces have the same integrated volume as the other cycles. Total inlet air is 300 × 6.40 = 1,920 L_ref. Accepted count is 300 − 12 = 288 packs. Air per attempted pack is 6.40 L_ref; air per accepted pack is 1,920/288 = 6.667 L_ref. Achieved accepted output is 28.8 packs/min over that run.

Interpretation: the accepted-product figure exceeds the cycle figure because rejected attempts consumed air. The blow-off interval also contains motion, so its 2.00 L_ref must not be labelled pure nozzle consumption without branch evidence. Adding a separate cylinder estimate to measured 6.40 L_ref would double count. This demonstrates the required measured-trace method with fictional data; real release requires a retained site trace for the named product and speed.

20 Worked case B Batch overhead and inventory correction

Continue the fictional Case A product and reference basis. Assume the batch window also includes 2 min ready time at a measured 30 L_ref/min and 40 L_ref of separately measured startup consumption. Startup and production totals cover disjoint intervals. Assume the 40 L_ref has already been reconciled to equivalent starting and ending stored inventory, and there is no additional rework outside the window.

Method: ready air = 30 × 2 = 60 L_ref. Batch volume = 1,920 + 60 + 40 = 2,020 L_ref. Batch air per accepted pack = 2,020/288 = 7.014 L_ref. Do not call this the steady-cycle value: its scope includes the stated startup and ready overhead. If startup duration is not recorded, batch average flow over total elapsed time cannot yet be calculated.

Separate inventory illustration: a fictional 20 L receiver at 293.15 K finishes a measured interval 0.50 bar below its starting pressure. With the same 1.000 bar(a) reference and ideal-gas approximation, inventory change is 20 × (−0.50)/1.000 = −10 L_ref. If the inlet totaliser reads 500 L_ref and there are no other boundary streams, consumed air is 500 − (−10) = 510 L_ref. The receiver supplied the additional 10 L_ref.

Interpretation: a depleted receiver makes inlet air smaller than internal consumption for that interval. A complete run including recharge avoids this particular bias. The inventory model assumes known effective volume and equal temperature; it is not a substitute for a validated transient-storage model when temperature changes materially.

21 Worked case C Cylinder and switched tubing demand

Hypothetical geometry screen only. Assume two identical single-rod double-acting cylinders, each with 40 mm bore, 16 mm rod and 100 mm full stroke, performing one extension and one retraction per packaging cycle. Assume both chambers fill at 7.000 bar(a), gas temperature is 293.15 K, reference is dry air at 1.000 bar(a) and 293.15 K, ideal-gas behaviour applies, and leakage and pilot consumption are excluded pending evidence. These are fictional calculation inputs, not approved operating settings.

Method per cylinder: cap swept volume = π × 40² × 100/4/1,000,000 = 0.125664 L. Rod-side swept volume = π × (40² − 16²) × 100/4/1,000,000 = 0.105558 L. Total swept volume is 0.231221 L. Converted swept demand is 0.231221 × 7/1 = 1.61855 L_ref per complete extension/retraction pair.

Assume the combined switched fixed tubing and dead volume charged once per complete pair is 0.040 L per cylinder. It begins each charge at 1.000 bar(a), ends at 7.000 bar(a), and returns to the same initial state over the pair. Its reference increment is 0.040 × (7 − 1)/1 = 0.240 L_ref. Combined demand is 1.85855 L_ref per cylinder pair, or 3.71710 L_ref per packaging cycle for the two cylinders. At an assumed 30 cycles/min, modeled average is 111.513 L_ref/min.

Interpretation: this component estimate supports reconciliation; it is not another term to add to Case A's inlet measurement. Subtracting it from 6.40 L_ref leaves about 2.683 L_ref for all remaining contributions and modeling differences, not a proven blow-off value. Verify strokes, chamber pressure, tubing switching, accessories and measurement uncertainty before interpreting that residual.

22 Worked case D Blow-off timing and acceptance

Hypothetical comparison only. Assume one nozzle has a separately measured supply flow of 240 L_ref/min during a stable air-on window, on Case A's reference basis. A baseline window is 0.35 s per attempted pack and a trial window is 0.20 s. Assume one pulse per attempt, 30 attempts/min, no material tail-flow difference, unchanged dynamic supply and no additional retry actions. Check these assumptions in an actual trial.

Method: baseline pulse = 240 × 0.35/60 = 1.40 L_ref. Trial pulse = 240 × 0.20/60 = 0.80 L_ref. Reduction is 0.60 L_ref per attempt, or 18 L_ref/min at the assumed rate. Over 300 attempts, modeled nozzle volumes are 420 and 240 L_ref, a difference of 180 L_ref.

To test the consequence, assume other machine air remains 1,500 L_ref over those 300 attempts. Baseline total is 1,920 L_ref with 288 accepted packs, or 6.667 L_ref/accepted pack. Trial total is 1,740 L_ref. If only 250 packs are accepted in the trial, the result is 6.960 L_ref/accepted pack despite lower nozzle air. At 270 accepted packs, it would be 6.444 L_ref/accepted pack, but quality and throughput criteria still require separate assessment.

Interpretation: the arithmetic identifies a yield tradeoff; it does not approve either outcome. For this fixed fictional total, more than 261 accepted packs are needed to beat the baseline ratio strictly. A lower air ratio cannot override mandatory product quality. Repeated clearing blows or off-line rework would change the trial numerator and must be included if present.

23 Worked case E Ready state and authorised standby

Hypothetical state comparison only. Assume a machine has ready-state inlet flow of 24 L_ref/min and a separately validated standby state at 4 L_ref/min, both measured at comparable inlet pressure on the same declared reference basis. Production is absent for 45 min. Approved standby retains required purge and safe conditions; switching to standby adds a measured 30 L_ref of recovery air before the next accepted production run.

Method: remaining ready consumes 24 × 45 = 1,080 L_ref. Standby consumes 4 × 45 = 180 L_ref, plus 30 L_ref recovery, giving 210 L_ref. The interval reduction is 870 L_ref. The state difference of 20 L_ref/min is not automatically leakage: it can include intentional functions disabled by approved standby logic.

Interpretation: compare the entire stop-and-restart interval. If restart creates extra rejects, their air and output effect must enter the comparison. No electricity, financial saving or standard payback is derived from this volume difference. Those require evidence about compressor controls, input power, operating duration and cost basis.

24 Worked case F Two machines and coincident pulses

Hypothetical sequencing example only. Each of two machines has a 2.00 s repeat period, a continuous 10 L_ref/min baseline and an additional 120 L_ref/min pulse lasting 0.25 s. Both streams use the same reference basis. Assume rectangular pulses, no missing loads, equal repeated-cycle inventory, and that the integrator permits the compared sequences.

Method per machine: baseline air = 10 × 2/60 = 0.3333 L_ref/cycle; pulse air = 120 × 0.25/60 = 0.5000 L_ref/cycle. The pair consumes 1.6667 L_ref per common 2.00 s period, giving an average 50 L_ref/min. If pulses align, the combined level during overlap is 10 + 10 + 120 + 120 = 260 L_ref/min. If fully staggered, the largest modeled level is 10 + 10 + 120 = 140 L_ref/min.

Interpretation: total reference air is unchanged by staggering. The lower modeled peak is valid only while overlap is prevented and does not establish pressure at either machine. Startup, speed mismatch and recovery can defeat a nominal offset. Attach the control interlock or evaluate the permitted coincident case. Do not apply the 140/260 ratio as a universal diversity factor.

25 Worked case G Multi-up packs and rework counting

Hypothetical counting example only. A fictional four-position machine completes 100 cycles. Assume all four positions are filled on every cycle, batch inlet total is 900 L_ref, beginning and ending inventory are equal, and 20 of the 400 attempted packs require one additional pass through a separately metered rework operation. Rework consumes 50 L_ref and produces 15 accepted packs; five packs are scrapped. All quantities use the same reference basis.

Method: first-pass accepted count is 400 − 20 = 380. Final unique accepted count is 380 + 15 = 395. For the combined production-and-rework boundary, total air is 900 + 50 = 950 L_ref, giving 950/395 = 2.405 L_ref per accepted pack. The first-pass-only result is 900/380 = 2.368 L_ref per first-pass accepted pack. These are different scopes and must keep their labels.

Interpretation: 100 cycles, 400 original products and 420 handling attempts describe different quantities. Counting the 15 recovered packs as new original products would distort yield. Adding rework air without including its recovered output would distort the combined ratio. A real record also needs treatment of work in progress and rework crossing the reporting window.

26 Diagnose a poor result before increasing supply

Use the observation to select a discriminating measurement. More compressor capacity can leave a local restriction untouched; a larger receiver can mask a recharge deficit during a short demonstration. Changing several settings together makes the cause harder to establish and can invalidate the comparison. Retain the original configuration, change one justified factor under the approved procedure, then repeat the relevant operating case.

A pressure problem and a quality problem can coexist. Restoring pressure may improve timing while contaminated air still reaches a sensitive surface. The diagnostic record should therefore retain product acceptance and air-quality evidence as separate lines. A corrected flow number alone does not close every consequence of the fault.

27 Compare improvements on a common basis

Create a baseline and trial record with the same product, recipe, boundary, reference state and accounting policy. If a condition must change, record the reason and its expected influence. Comparing a fast production run with a slow run that includes long gaps can reward a change in overhead allocation rather than a better pneumatic process. Report cycle quantity, accepted-product quantity, elapsed-state durations and pressure performance together.

Choose the improvement against the observed mechanism. A longer-than-needed jet window suggests a controlled timing trial. A repeated pressure dip across a connector suggests reviewing that restriction. A genuine continuous leak suggests repair. The evidence should support the chosen action rather than a preselected equipment purchase.

Where air demand falls, check whether compressor operation changes before estimating energy benefit. At the plant level, controls, unloading, minimum running capacity and other demand can affect electrical response. A reference-volume comparison supports an air-use statement. It does not by itself support an electricity percentage, cost saving or return-on-investment claim. Keep an unverified commercial result out of customer-facing copy.

28 Commission the machine and its utility interface

Agree the acceptance matrix before the test. Name the product, recipe, tooling, speed cases, supply boundary, simultaneous-machine cases, permitted pressure envelope, quality requirements and rejected-cycle treatment. Identify responsible machine, utility, production and quality reviewers. Obtain the applicable machine instructions and approved test procedure; this guide supplies evidence requirements, not authority to change protective settings or bypass interlocks.

Inspect the installed configuration against the reviewed arrangement. Confirm component identities, air connections, treatment, drains, hoses, regulation, instruments and control revisions. Check that meter installation has not introduced an unacceptable restriction. Record the applicable safe isolation and restart arrangements. Unknown ratings or unresolved product-contact requirements remain hold items, not values to infer from a nearby machine.

Run the agreed sequence through representative steady production, relevant speed changes, ready/standby, restart and permitted concurrent operation. Capture raw flow, pressure, state and count evidence. Confirm that the delivery condition recovers and does not progressively deteriorate as storage is depleted or treatment warms. Apply the predefined stop and investigation criteria when required. A successful short run cannot replace an omitted governing case.

Review air quantity and product outcome together. An acceptable pack count with an unresolved pressure excursion does not automatically establish the documented supply envelope; a stable air trace with failed seals does not establish product acceptance. Each responsible discipline should dispose of its own evidence and identify dependencies that keep overall acceptance open.

29 Write an acceptance statement that can be audited

Use a scoped statement: “Accepted for product [identity and format], recipe [revision], machine [identity], at commanded [value and unit] and observed [value and unit], for operating cases [list], with rejected-cycle treatment [policy], within boundary [drawing and measurement points], under criteria [approved references].” Record test duration, counts, reference state, dynamic pressure results, inventory treatment and deviations. Replace every bracketed field before marking a real duty accepted.

If a critical record is missing, use HOLD with an owner and closure evidence. Conditional acceptance should name the restricted operating case and who authorised it; it must not silently become general acceptance for all formats or speeds. Numerical calculation validation is separate from approval of an actual machine. The R01 release gate is not satisfied by writing “commissioned” beside an air-flow value.

Retain the approved record, raw measurements, calculation revision, component identities and change history. Reassess after recipe, speed, nozzle, cylinder, coupling, regulator, treatment, control logic or concurrency changes that can affect the duty. A replacement component with the same port size is not automatically equivalent in dynamic delivery. Record which evidence transfers and which test must be repeated.

30 Frequently asked questions

Can packs per minute determine compressor size

No. Packs per minute gives a rate, while reference air per cycle, continuous loads, product yield, simultaneous users and the required dynamic pressure define the utility demand. Establish those conditions before selecting a supply arrangement. An average flow calculation does not prove transient delivery.

Should valve flow capacity be added to cylinder consumption

No. A directional valve usually carries the same air that fills the cylinder. Its rated capacity describes delivery capability under stated conditions. Add distinct pilot, bleed or auxiliary consumption only when it is genuinely separate and not already included in the measured boundary.

Does a double-acting cylinder consume twice its extension air

Not necessarily. A single-rod cylinder has a smaller rod-side swept volume, and extension and retraction can use different pressures or partial strokes. Use the actual geometry and sequence or applicable supplier data. A full-stroke geometry calculation remains a model to check against the installed duty.

Does low idle flow prove a low-leakage machine

Only if the measurement can resolve that flow and the state and boundary are known. Some branches may be isolated while others operate continuously. Separate required purge, bleed, ejector duty and identified leakage before drawing a maintenance conclusion.

Can rejected cycles be removed from air per accepted product

Rejected attempts consume resources and remain in the numerator within the declared accounting scope. The denominator counts accepted products under an explicit first-pass or final-acceptance rule. Report excluded off-line rework openly or include it through a reconciled measurement.

Why can staggering machines help without reducing air use

Staggering can separate short demand pulses and reduce their common peak while leaving the integrated volume unchanged. It is useful only if the sequence is permitted and the phase relationship is controlled or otherwise justified. Verify pressure and recovery under the relevant restart cases.

Is one pressure reading enough for commissioning

A static reading cannot establish dynamic delivery through an entire cycle. Use measurements at the agreed interfaces with response suited to the events, aligned with flow and machine state. Acceptance limits must come from applicable equipment and process evidence.

Does an oil-free compressor prove product-contact suitability

No. Delivered air quality depends on the complete intake, generation, treatment and distribution path and the relevant contaminants. The responsible product-quality authority must define the condition and verification method at the actual contact point. No blanket food, pharmaceutical or sterile-air claim is established here.

Can the hypothetical example values be used as machine settings

No. They demonstrate methods with explicit assumptions. They do not state a machine's rated pressure, expected productivity, air quality or permitted control settings. Replace them with traceable project inputs and obtain the responsible engineering disposition.

31 Required asset Packaging Cycle Air Balance

Use one balance record for each materially different product, recipe, speed and machine configuration. The following editable records constitute the required asset; they can be completed in Word and copied for additional cases. Keep the shared record identifier on every copied sheet and attachment. The filled illustration in Section 32 demonstrates completion without representing a real accepted installation.

Start with identity and scope, then build the state and event records. Attach the trace before calculating performance ratios. Every numerical input needs a value, unit, basis, source identifier and evidence status. Use Unknown during preparation, but never convert it to zero. Distinguish MEASURED, DOCUMENTED, CALCULATED and ASSUMED inputs. A document reference must include revision and applicability, not simply “OEM”.

The disposition choices are DRAFT, READY FOR REVIEW, HOLD and ACCEPTED FOR STATED DUTY. DRAFT allows incomplete entries. READY FOR REVIEW means required evidence has been assembled, not that engineering is approved. HOLD names the missing or failed requirement and owner. ACCEPTED FOR STATED DUTY requires the designated reviewers and a completed product/speed/reject statement. A calculated number must never change the disposition automatically.

A Identity and operating envelope

B State and event record

Duplicate this record for each event or state. Use an event record for a cylinder movement, blow-off pulse or retry, and a state record for continuous demand over a duration. Assign each actual stream to a unique accounting owner. Mark rows that are explanatory subcomponents of a measured total so they are not added again.

Do not sum overlapping state durations as if they were mutually exclusive. Several events can overlap within one machine state, but each air stream must still be counted once. For whole-machine measurements, keep the interval partition non-overlapping and complete. Use branch measurements or a qualified model only to explain its components.

C Measurement and evidence record

D Result and balance reconciliation

A reconciliation residual is not automatically leakage. It may be a measurement limitation, incomplete component model or inventory change. State whether the residual matters to the intended decision and what evidence would close it. Do not label the balance accepted simply because a spreadsheet total adds correctly.

E Acceptance and action record

Product and format: [enter]. Recipe and tooling revision: [enter]. Machine and configuration: [enter]. Commanded and observed speed with units: [enter]. Accepted output over the named window: [enter]. Rejected-cycle, retry and rework treatment: [enter]. These fields are mandatory for a real acceptance decision.

Test scope and permitted concurrent cases: [enter]. Approved pressure, temperature, quality and product criteria with sources: [enter]. Raw evidence identifiers: [enter]. Result and restricted applicability: [enter]. Disposition: [DRAFT / READY FOR REVIEW / HOLD / ACCEPTED FOR STATED DUTY].

32 Filled illustrative balance record

Product “Example Carton A” denotes one hypothetical pack per cycle; it is not a customer SKU. Machine “Example Indexer A” and recipe “Example 1” are fictional labels. Commanded and observed cycle rate are both assumed to be 30 cycles/min for 10 min. Accepted output is 28.8 packs/min. The boundary is one machine inlet with all downstream branches included and no transfer streams.

Reference basis is dry air at 1.000 bar(a), 293.15 K. Source EX-TRACE-A is the interval-average table in Case A, repeated for 300 cycles. Starting and ending gas inventory are assumed equal. Count record EX-COUNT-A gives 300 attempts, 12 rejected packs and 288 accepted packs, with no rework and identical integrated air for rejected cycles.

The cylinder estimate in Case C is SUBCOMPONENT ONLY. It is not added to 1,920 L_ref. Blow-off timing in Case D and standby in Case E are separate hypothetical comparison cases, not extra rows in this production record. This separation prevents a reader from assembling unrelated examples into a fictitious machine rating.

33 Worked uncertainty and decision limits

Hypothetical sensitivity calculation only. Suppose Case A's integrated volume is reported with a bounded ±3% volume uncertainty for the stated measurement conditions and the count of 288 accepted packs is exact. The illustrative volume interval is 1,862.4 to 1,977.6 L_ref. Dividing by 288 gives 6.467 to 6.867 L_ref per accepted pack. This is a bounded input propagation, not an automatically assigned statistical confidence interval.

If the accepted count is also uncertain, the ratio needs that uncertainty addressed. For conservative independent bounds, use the smallest numerator with the largest plausible denominator for the lower ratio and the largest numerator with the smallest positive plausible denominator for the upper ratio. Correlated errors, sampling bias and missing states need a more suitable analysis. Repeating cycles can reduce some random variation but does not remove a systematic reference-basis error.

Agree the decision rule before comparing a measured result with a contractual threshold. A reviewer can require better measurement, a repeated operating case or a restricted conclusion when the evidence cannot resolve the decision. Keep the mathematical result and the engineering disposition separate in the asset and its export.