9
Pressure Test Instructions
 
Systems are pressure tested to ensure they are: 
 
 
 
Pressure testing is hazardous and should be carried out carefully: 
 
  
 
Nitrogen and regulation 
Dry (oxygen free) nitrogen (OFN) is used to achieve the pressures required for the 
pressure tests because it is inert.   You must never use oxygen for pressure testing - 
pure oxygen at high pressure reacts violently with oil and will explode. 
 
to the pressure required. 
 
Do not use a regulator with an 
output pressure much higher 
 
The pressure tests
Increase the pressure to approximately 5 bar g and check for leaks using leak 
detection spray at this pressure initially – many leaks will be identified at this 
pressure so you will not waste nitrogen and time.   It is also safer to find leaks at a 
lower pressure than the final test pressures. 
 
Increase the pressure slowly to the strength test pressure and hold it for 15 
minutes.   Under the Pressure Equipment Regulation this strength test might need 
to be witnessed by a notified body.    
 
Safe – for this test a pressure above the system’s maximum allowable 
pressure (PSi) is used
Leak tight – this test is at PSi. 
The nitrogen used for pressure testing is an asphyxiant, so the area around 
the system should be well-ventilated 
High pressures are used, so all non-essential personal should be evacuated 
from the area 
Anyone carrying out the pressure testing should wear safety goggles. 
2. Open the cylinder valve 
3. Slowly open the regulator 
 Page 24  
1. Ensure the regulator is 
closed (wound fully anti 
clockwise)