Compressed air receiver tanks

01

Size the receiver and set its design conditions

HSE's Compressed air safety guide (HSG39) says the required capacity depends on compressor output and demand pattern and, as a guide, is between six and ten times the compressor's free air output at normal pressure in litres per second; it warns that "many users try to save on initial cost and make the mistake of buying a receiver that is too small". New receivers should conform to BS EN 286-1 or BS 5169, or a standard of equal integrity. [1]

DFC's 500-gallon vertical air storage tank, built to ASME in SA-516M Gr.485 carbon steel, is rated at 1.1 MPa (159 psi, 11 bar) design pressure and 110 °C design temperature, with 1,000 mm inside diameter and 2 m³ (2,000 L) volume. [2]

Editorial calculation: by HSE's guide, a compressor delivering 100 L/s of free air would pair with a 600–1,000 L receiver. DFC's 2,000 L tank at 11 bar has a pressure × volume of about 22,000 bar·L, far above the 250 bar·L threshold at which HSE requires a written scheme of examination. [1] [2]

The US Department of Energy's sourcebook Improving Compressed Air System Performance (third edition, with the Compressed Air Challenge) sizes a receiver from the event it must cover: V = T × C × Pa ÷ (P1 − P2), with T the duration in minutes, C the air demand in cfm of free air, Pa absolute atmospheric pressure and P1 − P2 the allowable pressure drop, assuming the receiver is at ambient temperature and no compressor air is supplied; if a compressor runs during the draw, C is replaced by C − S, S being its surplus capacity. It says the old rule of thumb of 1 to 3 gallons per cfm of compressor capacity, from the reciprocating-compressor era, is no longer regarded as good practice, since the recommended size varies with compressor type and capacity control. It also estimates leakage from a timed pressure decay as V × (P1 − P2) ÷ (T × 14.7) × 1.25, and treats leakage above 10% as a sign the system can be improved. [3]

Editorial calculation: to supply 100 cfm for 3 minutes while the receiver falls from 95 to 70 psig, V = 3 × 100 × 14.7 ÷ 25 ≈ 176 ft³, about 1,320 US gallons or 5,000 L — far above what the 1–3 gal/cfm rule gives for a 100 cfm compressor (100–300 gallons). [3]

Give the supplier the compressor free air delivery and maximum pressure, demand pattern, required volume, design pressure and temperature, construction code (for example ASME, BS EN 286-1), orientation, connection sizes, corrosion allowance and coating, and site climate (freezing).

02

Fit the safety valve, gauge, drain and inspection openings

HSG39 says a receiver connected to a compressor should either withstand the compressor's maximum pressure or carry a safety valve and pressure-reducing valve; the safety valve must open as soon as safe working pressure is exceeded and be able to discharge more air than the system can supply. The receiver needs a pressure gauge, a manual or automatic drain (manual drains full bore and straight through; automatic drains with adequate capacity, a manual override and an upstream strainer, protected from freezing), and a manhole, handhole or other opening for internal cleaning and inspection. [1]

The receiver must be marked conspicuously with its safe working pressure and identified by markings or a maker's plate. For receivers above 250 bar litres, a written scheme of examination drawn up or certified by a competent person "will normally specify a period between examinations of 24 to 48 months", in HSE's words. On large compressor systems HSE recommends a fusible plug, and it warns against welding brackets onto receivers except to the manufacturer's specification, preferably via intermediate reinforcing plates. The main hazard it names is explosion from over-pressure or from strength lost to corrosion, fatigue or internal coke fires. [1]

03

Compare what suppliers offer

The suppliers linked to this page list air storage tanks; their cards link to the pages reviewed.

Ask any supplier for the design code and certificate, design pressure and temperature, volume and dimensions, material and plate thickness, corrosion allowance, weld inspection and hydrostatic test records, connection sizes, fittings supplied (safety valve, gauge, drain), coating and name plate data.

04

Check a US installation against OSHA's air receiver rule

US OSHA standard 29 CFR 1910.169 requires new air receivers to be built to the 1968 edition of the ASME Boiler and Pressure Vessel Code, Section VIII, with safety valves built, installed and maintained to the same edition. Every receiver needs a readily visible indicating pressure gauge and one or more spring-loaded safety valves whose total relieving capacity keeps receiver pressure from exceeding the maximum allowable working pressure by more than 10 percent, and no valve of any type may sit between the receiver and its safety valves. [4]

A drain pipe and valve must be fitted at the lowest point to remove accumulated oil and water, automatic traps may be added, and OSHA says the receiver must be drained "at such intervals as to prevent the accumulation of excessive amounts of liquid in the receiver". Drains, handholes and manholes must be easy to reach, and safety devices must be installed so they cannot readily be rendered inoperative, including by the elements. [4]

Editorial calculation: if DFC's 1.1 MPa (11 bar) design pressure is taken as the maximum allowable working pressure, the safety valves must hold the receiver at or below 12.1 bar (11 × 1.10). [2] [4]

05

Trace the receiver parts

This is a functional reference built from the sources cited; it is not one maker's specification.

06

Fill the specification fields with values for your system

An air receiver quotation needs values for your compressed air system. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

07

Send the compressor, code and fittings data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Compressor: [free air delivery; maximum pressure]
Demand: [pattern; peaks]
Vessel: [volume; design pressure; temperature; code]
Build: [orientation; connections; corrosion allowance; coating]
Fittings: [safety valve; gauge; drain; manhole]
Documents: [certificate; test records; name plate]

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