When selecting and operating air receiver tanks, many customers confuse working pressure with design pressure. These two core pressure parameters determine tank safety, service life and compliance with pressure vessel codes.
Definitions
Working Pressure (Operating Pressure, Pw)
The stable actual internal pressure inside the tank during regular production operation, which is the standard pressure set for daily air supply.For example: If the air compressor is regulated to 0.8 MPa for daily use, 0.8 MPa is the working pressure.
Design Pressure (Pd)
The reference pressure for pressure vessel design, manufacturing, inspection and acceptance, representing the maximum limiting pressure the air tank can safely withstand with safety margin reserved.Design pressure of air receiver tank is always higher than working pressure.
Comparison Table
Comparison Item |
Working Pressure |
Design Pressure |
Application |
Daily operating pressure |
Basis for calculating tank wall thickness, welds, head and safety valve |
Value |
Relatively low |
Higher than working pressure with safety margin (normally +0.1~0.2 MPa) |
Application Logic |
Determined by on-site air demand |
Increased per codes to reserve safety allowance |
Safety Range |
Long-term stable operating range |
Only allowed for transient pressure surge, no long-term operation at this level |
Safety Valve Setting |
Safety valve cracking pressure higher than working pressure |
Safety valve cracking pressure close to design pressure but lower than it |
Nameplate Marking |
Not marked separately |
Mandatorily marked on air receiver tank nameplate |
Practical Example
If the customer requires stable air supply at 0.8 MPa (working pressure = 0.8 MPa), the standard air receiver tank supplied by the factory has a design pressure of 1.0 MPa:
1. The compressor stops when pressure reaches 0.8 MPa under normal operation, which is within the working pressure range.
2. The safety valve cracking pressure is set at approx. 0.95~0.98 MPa, lower than the design pressure 1.0 MPa.
3. The steel plate thickness, welds and heads of the tank are all manufactured based on the strength standard of 1.0 MPa with safety allowance, to avoid tank rupture caused by pressure fluctuation and surge.
Key Code Requirements
1. Long-term operation above working pressure is strictly prohibited Short-term pressure fluctuation is acceptable, but sustained pressure near design pressure will cause fatigue damage to the tank.
2. Design pressure is the legal maximum safety limit Hydrostatic test, non-destructive testing and third-party supervision inspection are all carried out against design pressure. Sustained pressure exceeding design pressure is severe illegal and dangerous operation.
3. General Selection Reference
· Working pressure ≤ 0.7 MPa → Select design pressure 1.0 MPa
· Working pressure 0.8~1.0 MPa → Select design pressure 1.3 MPa
4. Safety Valve Logic
Normal working pressure ＜ Safety valve cracking pressure ＜ Tank design pressure
YCZX air receiver tanks are strictly designed and inspected in accordance with international pressure vessel standards, with sufficient safety pressure margin reserved for various industrial working conditions. If you have specific air pressure requirements, we can provide customized air tank solutions with matched design pressure for your project.
