What is a tank-mounted screw compressor?
In a tank-mounted package, the compressor, motor, cooler and controls sit on a frame fixed above a horizontal air receiver. The discharge air goes into the receiver, and the plant takes air from the receiver outlet. Many designs also include a refrigerated dryer, mounted on the frame or beside it, and sometimes filters, giving a complete compressed-air station in one footprint.
Representative images of machine types we sell, service and rent. Models and capacities are confirmed against your duty.
The arrangement is most common on small and lower-medium screw compressors, roughly from about 3.7 to 22 kW (5 to 30 hp). Receiver sizes on these packages commonly range from about 200 to 500 litres, depending on the manufacturer. Larger compressors are normally base-mounted, with a separate receiver sized for the system.
Why choose a tank-mounted package?
- Floor space: compressor, receiver and dryer share one footprint, which helps in tight workshops and rented units.
- Simpler installation: fewer pipe connections, less site fabrication, and one electrical connection when the dryer is integrated.
- Factory-matched components: the dryer and receiver are chosen by the manufacturer to suit the compressor.
- Quicker commissioning: the package arrives largely ready, which matters when a plant is starting up or replacing a failed machine.
- Cleaner layout: a single unit is easier to keep tidy, ventilate and service.
Across brands
Models we supply and service
Manufacturer product images, shown to identify machines we sell, service and support. Brand names are trademarks of their owners.
Tank-mounted vs base-mounted with separate receiver
| Factor | Tank-mounted package | Base-mounted with separate receiver |
|---|---|---|
| Footprint | Smallest | Larger; receiver placed separately |
| Receiver size | Fixed by the package | Chosen for the system demand |
| Installation work | Minimal | More piping and fabrication |
| Flexibility | Limited; adding storage means another vessel | Easy to arrange wet and dry receivers |
| Vibration and noise | Package design must isolate the compressor from the tank | Compressor on its own base |
| Service access | Can be tighter around the dryer and drain | Usually easier |
| Typical use | Workshops, CNC shops, small plants, single-compressor systems | Medium and large plants, multiple compressors |
Is the built-in receiver big enough?
The receiver on a tank-mounted package is a convenience, not a substitute for proper storage design. It may be adequate for steady demand, but too small when the plant has large, short peaks such as blow-off, sandblasting or large cylinders firing together.
A widely used estimate for receiver volume is:
V = t × C × Pa ÷ (P1 − P2)
where V is the receiver volume, t the duration of the peak in minutes, C the excess air demand above compressor output in m³/min of free air, Pa the atmospheric pressure (about 1 bar absolute), and P1 − P2 the allowable pressure drop in bar during the peak.
Worked example: a peak demands 0.6 m³/min more than the compressor can deliver for 1 minute, and the plant can accept a fall from 8 to 7 bar. V = 1 × 0.6 × 1 ÷ 1 = 0.6 m³, or about 600 litres. A package with a 270-litre tank would not cover this peak, so a second receiver near the user or a larger compressor would be needed.
Too little storage also makes a fixed-speed compressor cycle often between load and unload, increasing wear and energy use. Most manufacturers state a maximum number of motor starts per hour, which a small receiver can push the machine towards.
How to select a tank-mounted package
- Size the compressor first. Add up simultaneous demand at working pressure, allow for leaks and growth, and select by FAD measured to ISO 1217.
- Choose the right pressure variant. Typically 7.5, 8.5 or 10 bar (about 110, 125 or 145 psig). Avoid running higher than needed; each extra bar costs about 7% more power.
- Check storage against peaks. Use the receiver formula above and add a separate receiver if the built-in one is too small.
- Decide on the dryer. An integrated refrigerated dryer (pressure dew point typically around +3 °C) suits most workshops; specify a desiccant dryer separately where lower dew points are needed.
- Plan the location. Confirm the floor can carry the full package weight, the room can be ventilated, and there is access to the drain, dryer and filter elements.
- Check vessel documentation. The receiver should come with its design pressure, test certificate and safety valve rating from the manufacturer.
Receiver safety and inspection
An air receiver is a pressure vessel storing a large amount of energy. A tank-mounted package does not change the safety requirements:
- The safety valve must be set at or below the vessel’s design pressure, sized for the compressor’s full output and tested periodically.
- The pressure gauge must read correctly.
- Condensate must be drained regularly; standing water corrodes the vessel from inside, and Hyderabad’s humid months produce a lot of condensate.
- The vessel should be inspected internally and externally at the intervals required by the applicable rules and the manufacturer.
- Any welding, drilling or modification of the receiver must be avoided unless done under proper engineering control.
Our air receiver inspection and safety page explains these checks in more detail.
Common problems with tank-mounted packages
| Problem | Common causes | Fix |
|---|---|---|
| Compressor cycles too often | Receiver too small for demand pattern, narrow pressure band | Add downstream receiver, adjust band |
| Water in the plant lines | Tank drain blocked or not operated, dryer bypassed or failed | Service drain, repair dryer |
| Overheating in summer | Package installed against a wall, hot air recirculating, dusty cooler | Clearances, ducting, cooler cleaning |
| Excessive vibration | Worn mounts, loose fixings, floor not level | Replace mounts, level and fix the package |
| Rust or pitting inside the tank | Long-term standing condensate | Inspection, regular draining, assess vessel fitness |
Servicing a tank-mounted package
The compressor is serviced like any screw machine: intake filter, oil, oil filter, separator, coolers and belts where fitted. The additions are the receiver drain, which should be checked daily or fitted with a reliable automatic drain, the integrated dryer’s condenser and drain, and the safety valve. Because the components sit close together, keep them clean of dust so that air flows freely across coolers and the dryer condenser. Our rotary screw service and dryer service pages cover these routines.
Where tank-mounted packages work best
Tank-mounted packages suit plants where one compressor serves a compact area and demand is fairly steady. Typical examples are:
- CNC and tool-room shops with several machining centres running through a shift.
- Automotive service centres and tyre shops with a mix of impact tools, lifts and inflation.
- Small packaging, printing and plastics units with cylinder and gripper loads.
- Laboratories, dental clinics and small hospital workshops, usually with oil-free or well-filtered air.
- Rented or shared industrial units where floor space is scarce and the layout may change.
They are less suited where several compressors must share a common header, where demand is spread across a large site with long pipe runs, or where the process needs large buffer storage. In those cases a base-mounted compressor feeding a separately sized wet receiver, followed by the dryer and a dry receiver, gives better control of pressure and moisture. When an existing plant grows, a tank-mounted machine can often stay in service as a second or standby compressor alongside a larger base-mounted unit.
How Reddy Compressors helps
Reddy Compressors, based at Tarnaka, Secunderabad since 2002, is an independent multi-brand specialist, not an authorised dealer. We have tie-ups with all major and reputed brands. We sell new and used/refurbished tank-mounted screw compressors from ELGi, Atlas Copco, Ingersoll Rand, KAESER, Chicago Pneumatic and other makes, and rent, service and supply spares for them.
- We size the compressor and check whether the built-in receiver is enough, adding storage where peaks demand it.
- We advise on location, ventilation, drains and piping so the package performs in hot Indian summers.
- Our team of over 20 service engineers and technicians handles service, AMC and breakdown repair across Telangana and Andhra Pradesh.
- We supply compressor, dryer and receiver spares across India, identified from the nameplate and serial number with fit confirmed before quoting.
- We can provide a rental compressor during repairs or while a new package is delivered.
What to send us
- List of air-using machines and tools, with pressure and consumption if known.
- Details of any peak demands: what they are and how long they last.
- Available space with dimensions and photos of the location.
- Required air quality, such as general use, painting or food contact.
- For an existing package: make, model, serial number, nameplate photo and receiver nameplate.
- Your supply voltage and shift pattern.
Frequently asked questions
Is a tank-mounted screw compressor better than a separate receiver?
It is better for saving space and installation work, and it suits single-compressor systems with steady demand. A separate receiver gives more freedom to size storage for the system and to place it where demand peaks occur. Many plants use both: a tank-mounted package at the compressor and an extra receiver near large intermittent users.
What size receiver comes with a tank-mounted compressor?
It depends on the manufacturer and model; small packages commonly have receivers from about 200 to 500 litres. Check the vessel nameplate for volume and design pressure. Whether that is enough depends on your demand pattern: use the peak demand, its duration and the allowable pressure drop to calculate the storage you actually need.
Can I add another receiver to a tank-mounted compressor?
Yes. An additional receiver downstream of the dryer, often near a large intermittent user, provides extra storage and reduces compressor cycling. It needs its own safety valve, gauge and drain, and the piping between them should be sized for low pressure drop. This is a common, inexpensive improvement where the built-in tank is too small.
Why does my tank-mounted compressor start and stop so often?
Frequent cycling usually means the storage is too small for the demand pattern, the pressure band is too narrow, or the compressor is oversized for the load. Leaks can also cause it during idle periods. Check the receiver size against the peaks, review the control settings and carry out a leak check. Excess cycling wastes energy and increases motor and valve wear.
How often should the receiver on a tank-mounted package be drained?
At least daily if drained manually, and more often in humid weather. An automatic drain is better, provided it is checked regularly for blockage. Standing water in the tank causes internal corrosion and carries moisture into the dryer and the plant. Also have the vessel inspected at the intervals the applicable rules and manufacturer specify.
Are tank-mounted screw compressors suitable for CNC machines?
Yes, they are a popular choice for CNC shops because they combine compressor, storage and often a refrigerated dryer in one compact package. Size the compressor from the machines’ actual consumption and pressure, confirm the air quality the CNC manufacturer specifies, and add filtration where needed. Good ventilation is important, as CNC shops are often enclosed.
Related pages
Calculators and worked examples
These tools give indicative figures for screening, comparison and for preparing an enquiry. They run in your browser and send nothing. No prices or tariffs are assumed: enter your own to see costs. Efficiencies and other figures shown are example values: replace them with your own. Results are not a performance guarantee or a design certificate; final selection is confirmed by a service engineer against the machine data sheet and the site.
Receiver storage sizing
Estimate the receiver volume needed to ride through a short burst of demand without the pressure falling below the limit.
The worked example below shows the method with fixed numbers. Turn on JavaScript to change the inputs.
Worked example
Inputs
- Burst demand above compressor output (m³/min free air): 5
- Burst duration (s): 20
- Allowed pressure fall (bar): 0.7
- Receiver volume you already have (litres; 0 to skip the hold-up check): 1520
Result
- Receiver volume needed: 2,412 litres
- 2.41 m³
- Practical size (with 25% margin): 3,016 litres
- Hold-up time of the receiver you have: 12.6 s before the pressure falls by 0.7 bar
Method. V = Q × t × P_atm / ΔP, where Q is the shortfall in free air (m³/min), t the time (min), ΔP the allowed pressure fall (bar) and P_atm = 1.013 bar. The same relation gives the hold-up time of an existing receiver: t = V × ΔP / (Q × P_atm). Isothermal; for a real system add a margin.
What to take from it. A receiver buys time. It does not create capacity: once it is spent the pressure keeps falling until the compressors catch up.
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.