TL;DR — Direct answer: A pump and valve factory needs clean, dry air at 7 to 8 bar for machining, assembly and pressure testing, with a pressure dew point of 3 degrees C and filtration to 0.01 micron so no oil, water or particles reach a machined sealing face, a test gauge or a valve seat. Size on the coincident peak of machining, assembly and testing, commonly 6 to 13 cubic metres per minute for a mid-size plant, and use a variable speed drive because machining and testing loads swing across the shift. QiAir, a Chinese screw compressor manufacturer and supplier, builds fixed and variable speed machines for pump and valve production.
A pump or a valve is a machine that must seal under pressure for years, and the air behind it has to match that standard. Compressed air drives CNC machining centres and their tool changers, feeds casting cleaning and shot blasting, powers assembly tools for impellers, seals and actuators, and operates the test bays where every pump and valve is pressure and leak tested before it ships. A pressure dip at the wrong moment can stall a torque tool on a flange bolt, starve a blasting cabinet mid-cycle, or leave a test result unreliable, and a valve that passes a bad test can fail in service. QiAir is a Chinese manufacturer and supplier of screw air compressors, and its machines are specified for exactly this kind of heavy, mixed machining, assembly and testing duty.
The trap in pump and valve manufacturing is sizing air like a general factory utility. Machining is steady, assembly is intermittent, and testing draws sharp peaks when several test bays pressurise at once. The compressor must cover the coincident peak without sagging below 7 bar at the farthest test bay, and the treatment chain must hold the dew point and oil level steady through the hottest, most humid month. This guide maps the air users on a pump and valve line, explains how to size for machining and testing peaks, sets the air-quality standard that protects sealing faces and test results, and shows what to put on a sizing sheet for a China supplier.
Where Air Is Used: Machining, Assembly and Pressure Testing
Machining is the volume user. CNC machining centres use air for tool changers, spindle cooling and chip removal on pump casings, impellers and valve bodies, and the load is steady but spread across many machines at once. A machining hall with ten to twenty centres can pull its peak when several machines change tools together, and a compressor sized on average flow will sag exactly then. Cast iron dust and cutting fluid mist fill the air in this hall, so keep the compressor intake away from the machining area, check the intake filter weekly, and keep a spare on the shelf.
Assembly and testing are the sensitive users. Assembly lines use air for impact wrenches, torque tools, seal fitting and actuator mounting, and test bays use it for pressure and leak testing, seat leakage checks and final inspection. A test result is only as good as the air behind it: wet air in a test line can leave moisture inside a valve that later corrodes a seat, and a pressure swing during a leak test can mask a real leak or flag a good valve as faulty. A plant that maps every user, including the small air tools used for cleaning, usually finds 15 to 20 percent more demand than the original estimate.
- Machining: CNC tool changers, spindle cooling and chip removal across many centres at once.
- Assembly: torque tools, seal fitting, actuator mounting and casting cleaning.
- Testing: pressure and leak testing, seat leakage checks and final inspection at stable pressure.
Sizing for Machining Peaks and Test Loads
List every line with its flow at tool change and at steady running, because the two differ sharply in pump and valve work. A mid-size plant with ten to twenty machining centres, two to four assembly lines and two to four test bays typically peaks at 6 to 13 cubic metres per minute at 7 to 8 bar, which is roughly a 37 to 90 kW screw compressor, and the peak usually lands when several test bays pressurise together and the machining hall is at full load. A variable speed drive earns its keep here: it follows the mixed pattern instead of loading and unloading a fixed-speed machine dozens of times a shift, and it holds pressure within the narrow band that testing prefers.
Keep the pressure drop to the farthest test bay under 0.3 bar at peak flow, and fit a receiver of 500 to 1000 litres per 10 cubic metres per minute to absorb test-pressurisation spikes. A ring main helps when the machining hall, assembly shop and test bays sit in different wings of the building. Log pressure at the test bay during a full production run for a week, because that log is the honest record of whether the compressor is big enough, and it settles arguments faster than any catalogue figure. Never raise the set point to mask a sag: every extra bar adds roughly 7 percent to power use and hides the real fault, which is usually a clogged filter or an undersized pipe.
- Size on the coincident peak of machining and testing, not on steady-state average flow.
- Use a variable speed drive for mixed machining and testing loads, and keep far-end pressure drop under 0.3 bar.
- Log test-bay pressure during production for a week to prove the sizing in real use.
Test Air Quality: Dry, Clean and Stable
A leak test is only as honest as the air that runs it. Wet air in a test line leaves moisture inside a pump or valve that later corrodes a seat or a sealing face, oil aerosol can contaminate a seal and change how it seats, and a pressure swing during a leak test can mask a real leak or flag a good valve as faulty. The standard that prevents this is a treatment chain, not a single filter: a pre-filter, a refrigerated dryer to a 3 degree C pressure dew point, a coalescing filter to 0.01 micron, and an activated-carbon filter where the test specification demands oil-free quality air. For the test bays themselves, fit a final point-of-use filter at each bay, because that is the last chance to catch contamination before it reaches a valve under test.
Maintenance is what keeps that chain honest. Change coalescing elements on pressure drop, not on a calendar guess, and test the air at the test bay quarterly with a simple oil and moisture check. Drain condensate with automatic zero-loss drains, slope lines to drain legs, and keep the compressor room clean and ventilated so the machine does not breathe cast iron dust or its own hot air. A dryer that is undersized for summer humidity is a common failure in pump and valve plants in hot climates: size the dryer for the hottest, most humid month, not the annual average, and check the dew point at the dryer outlet every month.
- Fit pre-filter, refrigerated dryer, 0.01 micron coalescing filter and carbon filter where oil-free air is specified.
- Fit a final point-of-use filter at each test bay to protect the most sensitive testing work.
- Test air at the test bay quarterly, and size the dryer for peak summer humidity.
Buying from China: Sizing Sheet for a Pump and Valve Plant Compressor
QiAir is a Chinese manufacturer and supplier of screw air compressors, and a pump and valve order should start with a sizing sheet that names the process mix. Send the supplier the number of machining centres, assembly lines and test bays, the coincident peak at 7 to 8 bar, the air-quality standard the test specification requires, ambient temperature and humidity, and the distance to the farthest test bay. Ask for a quotation that states the filtration grades and dryer duty explicitly, and ask whether a filtered oil-injected machine or an oil-free machine fits the test specification better, with the cost and maintenance difference spelled out.
Agree the acceptance test before shipment: a full-load run at rated pressure, a dew point reading at the dryer outlet, and an oil-aerosol check at the final filter outlet. On arrival, install on a level plinth with clear cooler airflow, connect drains before the first run, and survey pressure at the test bay during a full production run in the first production week. Keep a log of pressure, dew point and filter changes, and review it monthly, because a slow rise in dew point is the earliest sign that a dryer needs attention before test results start drifting.
- Send the supplier machining, assembly and test bay counts, coincident peak, test air-quality standard and farthest-bay distance.
- Ask for filtration grades and dryer duty in writing, and compare oil-free against filtered oil-injected on total cost.
- Accept on a full-load test plus dew point and oil-aerosol checks, then survey pressure at the test bay in week one.
Frequently asked questions
What air quality does pump and valve manufacturing need?
Most pump and valve plants need dry air at a 3 degree C pressure dew point with coalescing filtration to 0.01 micron, and an activated-carbon filter where the test specification demands oil-free air. Fit a final point-of-use filter at each test bay, and test the air there quarterly for oil and moisture.
What size screw compressor does a pump and valve factory need?
A mid-size pump and valve plant with ten to twenty machining centres, two to four assembly lines and two to four test bays typically needs 6 to 13 cubic metres per minute at 7 to 8 bar, roughly a 37 to 90 kW screw compressor. Size on the coincident peak when machining and testing run together, and use a variable speed drive to follow the mixed load.
Why does compressed air affect pressure-test results?
Wet air leaves moisture inside a pump or valve that corrodes seats and sealing faces, oil aerosol contaminates seals and changes how they seat, and a pressure swing during a leak test can mask a real leak or flag a good valve as faulty. A dryer to a 3 degree C dew point, 0.01 micron coalescing filtration and a final filter at each test bay prevent most of it.
Related reading
- Single-Stage vs Two-Stage Screw Compressors: Which One a China Manufacturer Recommends
- Buying Screw Compressors from China: A Ranking Checklist for Choosing a Supplier
QiAir is a Chinese manufacturer and supplier of screw air compressors. If you are sourcing a screw compressor from China — for a factory, a food plant, a construction site or a new production line — contact QiAir for a sized quotation, documented performance data and export support.