What counts as a distribution improvement?
The distribution system is everything between the compressor station and the point of use: receivers, treatment, the main header, branch lines, drops, valves, filters, regulators, hoses and quick couplings. An improvement is any physical change that alters how much pressure is lost between the station and the user, or how evenly air reaches different parts of the plant.
Typical interventions include:
- Increasing header or branch diameter where velocity is too high.
- Closing a dead-end header into a ring main so users are fed from two directions.
- Replacing corroded galvanised pipe with aluminium or stainless systems with a smoother bore.
- Removing undersized ball valves, elbows, tees and quick couplings that act as restrictions.
- Moving take-offs to the top of the header so condensate does not flow into drops.
- Adding a local receiver near a large intermittent user.
- Replacing undersized hoses, or shortening long hose runs, on tools and machines.
- Replacing choked line filters and checking regulator capacity at the machine.
A single project often combines several of these. Each change should be recorded separately, with its location, drawing revision and installation date, because “network upgraded” tells nobody which change produced the result.
Why pressure loss in the network matters
Every bar lost in the pipework has to be made up at the compressor. As a typical rule, generating air at one bar higher discharge pressure takes about 7% more power for the same flow. Plants that suffer low pressure at a remote machine often raise the compressor setpoint instead of fixing the bottleneck, which costs power across the whole station and increases leakage, because leaks flow more at higher pressure.
A well-laid-out network typically loses only a small fraction of a bar from the compressor discharge to the furthest user at full flow. Where the loss is well over a bar, there is usually a specific restriction to find: an undersized branch, a clogged filter, a half-closed valve, a long hose or a dead-end header that starves its far end at peak demand.
The aim of a verified project is to show, with measurement, where the loss was, what was changed and how much of the loss was removed under comparable demand. Our network design and calculation pages cover the engineering of pipe sizing; this page covers how a completed change is checked and documented.
Defining the before-and-after boundary
Before any work starts, mark up a dated drawing of the system that shows:
- Compressor discharge points and the station control pressure signal.
- Wet and dry receivers, dryers and filters, with their positions in the line.
- The main header, branches, loops, cross-connections and isolation valves.
- Every pressure tap, logger and flow meter used for the comparison.
- The critical users whose pressure decides whether the plant runs properly.
The same points must be measured before and after the change. Moving a pressure gauge from one side of a filter to the other between the two periods is enough to make the comparison meaningless. If a new tap is added during the work, the baseline at that point simply does not exist and should not be estimated.
How the comparison is measured
Pressure loss in pipework rises steeply with flow. A spot reading on a quiet afternoon cannot be compared with a reading taken at full production. A sound comparison therefore logs pressure and flow together over representative operating periods.
- Log a baseline. Record pressure at the station and at each critical user, plus total flow, over at least one full production cycle, including shift changes and peak events.
- Record operating conditions. Note production schedule, compressors running, setpoints, dryer and filter condition, and ambient conditions.
- Make the change. Record each intervention with work order, date and drawing revision. Pressure-test new pipework to the applicable procedure before it goes into service.
- Repeat the logging. Use the same instruments and points, over a period with similar demand.
- Compare at matched flow. Plot pressure drop against flow for both periods and compare at the same flow band, not average against average.
- Check the critical users. Confirm whether the minimum pressure at each critical user now stays above its required value during peak events.
Where flow cannot be measured directly, the comparison must say so, and any claim must be limited to what the pressure records alone can show.
Illustrative example: reading the result correctly
The following figures are invented to show the method and do not describe a customer project.
| Measurement | Before | After | What it tells you |
|---|---|---|---|
| Station discharge pressure | 7.5 bar (108.8 psig) | 7.5 bar (108.8 psig) | Setpoint unchanged, so the comparison is fair |
| Pressure at remote machine, at peak flow | 6.2 bar (89.9 psig) | 6.9 bar (100.1 psig) | About 0.7 bar of loss removed at that point |
| Total station flow, peak band | Similar | Similar | Comparison is at matched demand |
| Change made | Dead-end branch closed into a loop; two undersized quick couplings replaced | ||
With the remote machine now receiving more pressure than it needs, the plant may be able to lower the station setpoint. That is a second, separate intervention. Using the typical 7% per bar rule, a 0.5 bar reduction would suggest roughly 3–4% less compressor power at the same flow, but the actual effect must be confirmed with electrical measurement after the setpoint change, because compressor control behaviour, part-load running and leakage all influence the outcome.
Confounders that can mislead a comparison
Many distribution projects appear more successful, or less successful, than they really were because something else changed at the same time. Check and record each of the following:
- Leak repairs. Fixing leaks during the same shutdown reduces flow and therefore pressure drop. The improvement then belongs partly to the leak work.
- Filter changes. A new element in a line filter can remove a large part of the loss on its own.
- Production changes. A new shift pattern, a stopped line or a new machine alters demand.
- Compressor changes. A different machine running, a changed setpoint or a control upgrade changes station behaviour.
- Dryer condition. A dryer with a fouled heat exchanger or failing drain changes both pressure loss and moisture carry-over.
- Instrument changes. A different gauge or logger, or one with a different accuracy, can introduce an apparent change that is not real.
Where several changes happened together, the honest description is the combined result of all of them, not a claim for one in particular.
Unintended consequences to look for
Improving one part of a network can shift problems elsewhere. A larger branch may let one area draw more air at peak, starving another. A new ring main may move condensate into drops that were previously dry if take-offs are not from the top of the pipe. Removing a pressure regulator to “gain pressure” can raise consumption at open blowing nozzles and actually increase total demand. A sound record reports these effects as clearly as the improvements.
How verified project evidence is classified
| Evidence type | What it supports | What it does not support |
|---|---|---|
| Dated drawings and work orders | What was physically changed and when | Any performance result |
| Matched pressure and flow logs | Reduced pressure loss at stated points and flow | Energy savings |
| Critical-user pressure logs | Whether the user now stays within its required pressure | Production or quality improvement |
| Electrical logs after a setpoint change | Measured change in compressor input under stated conditions | Annual savings without a defined method |
| Customer statement | The customer’s own view of the outcome | Measured engineering results |
We only publish project records that can be traced to such evidence and that the customer has agreed may be described. Customer names are not published. Where we have no measured distribution project to show for a particular claim, we explain the method rather than offering an example as if it were real.
How Reddy Compressors helps
Reddy Compressors, based at Tarnaka in Secunderabad and serving industry since 2002, works on compressed-air systems of all major brands, including Atlas Copco, Ingersoll Rand, ELGi, KAESER, Chicago Pneumatic, Gardner Denver, Sullair, Doosan and Kirloskar. We are an independent multi-brand specialist, not an authorised dealer of any brand. We have tie-ups with all major and reputed brands.
For distribution problems we can carry out air audits and pressure-drop surveys, log pressure and flow at agreed points, identify restrictions, and advise on header, loop and drop changes. Our service team of over 20 service engineers and technicians covers the whole of Telangana and Andhra Pradesh, and we supply compressors, rentals and spares across India. Where a network change needs a shutdown, we can provide rental compressors from our own fleet to keep critical users supplied. After the work, we repeat the measurement at the same points so that the result is documented rather than assumed.
What to send us
- A sketch or drawing of the network, showing compressors, receivers, dryers, header and main users.
- Compressor makes, models and setpoints, with photographs of nameplates.
- The users that suffer low pressure, with their required pressure and when the problem occurs.
- Pipe sizes and materials where known, and any recent changes.
- Any existing pressure, flow or power readings.
Frequently asked questions
How do I prove a compressed-air piping upgrade worked?
Log pressure at the compressor and at the critical users, together with total flow, before and after the change, using the same instruments at the same points. Then compare the pressure drop at the same flow band. If the remote users stay above their required pressure during peak demand after the change, and nothing else significant changed at the same time, you have reasonable evidence that the piping work caused the improvement.
Does a bigger air pipe always save energy?
No. A bigger pipe reduces pressure loss, but compressor power only falls if the station setpoint is then lowered or the compressors run less. If the setpoint stays the same, the users simply receive higher pressure and may even consume more air through open nozzles and leaks. Energy savings must be confirmed by measuring compressor input power after any setpoint change, not assumed from the pipe change.
What is an acceptable pressure drop in a compressed-air system?
A well-designed network typically loses only a small fraction of a bar between the compressor discharge and the furthest user at full flow, with the dryer and filters adding their own drop. If the loss is more than about one bar, there is normally a specific restriction worth finding, such as an undersized branch, a blocked filter, a long hose or a dead-end header.
Why should flow be measured along with pressure?
Pressure loss in pipework rises steeply as flow increases, so a reading taken at light load cannot be compared with one taken at peak production. Measuring flow lets you compare the before and after periods at the same demand. Without flow data, an apparent improvement may simply reflect a quieter day, fewer machines running or leaks repaired at the same time.
Is a ring main better than a single header?
Usually, yes, for plants with users spread across a large area. A ring main feeds each point from two directions, which roughly halves the flow path length and reduces pressure loss at the far end. It also allows a section to be isolated for maintenance without stopping the whole plant. It still needs correct sizing, drainage points and top-entry take-offs to work well.
Can you supply air while our pipework is being changed?
Yes. We rent diesel and electric compressors from 50–2,000 cfm at 2–30 bar (29–435.1 psig) from our own fleet, with hoses and treatment where needed. A temporary machine can be connected to the live section or directly to critical users while the header is modified, so production can continue during the work.
Related pages
Technical content reviewed by D. Srinivas Reddy, Managing Partner and service engineer, Reddy Compressors. Last updated 17 October 2026. How our engineering content is reviewed.