Parker Hannifin Corporation
Pneumatic Division Europe
www.parker.com/pde
2
FRL-SIF-120
_EU
Parker Pneumatic
Integration Guide
P33 Safety Exhaust Valve
Exhaust Times and Faulted Flow Rates
When designing a safety circuit, the machine stopping time is critical to the placement of guarding equipment – safe
distance. One factor in safe distance calculations is the exhaust time of the valve that is responsible for isolating and
dumping the pneumatic energy from the machine. The faster your valve exhausts the quicker the machine can stop
and the closer your safety devices may be placed to the hazardous area. This can improve the overall operating
efficiency, and possibly allow the footprint of the machine to be smaller.
Even more important than exhaust times is the “Faulted exhaust flow rate”. Faulted exhaust flow rate is the exhaust
rate of the valve in its worst state. Double valves (redundant valve systems used for safety applications) will not
exhaust quite as quickly when there is an internal fault condition in the valve such as when one of the redundant
valve components is actuated and the other one is not actuated. For this reason, double valves used in safety circuits
should always be sized using faulted flow rates as the worst case condition.
The chart below shows Parkers very high flowing faulted exhaust flow times.
Exhaust Sound Pressure Level
The P33 Safety Exhaust Valve has a sound pressure level of 88dB*
*dB is based on faulted condition, average and peak at 30 psi.
Exhaust Time - Normal and Faulted Conditions (s)
Volume
ft3 (L)
Normal or
Faulted
Operating Pressure
30 psig (2 bar)
90 psig (6 bar)
145 psig (10 bar)
to 15 psig
(1 bar)
to 7 psig
(0.5 bar)
to 15 psig
(1 bar)
to 7 psig
(0.5 bar)
to 15 psig
(1 bar)
to 7 psig
(0.5 bar)
0.071 (2)
N
0.05
0.07
0.09
0.11
0.12
0.14
(F)
0.07
0.10
0.15
0.18
0.20
0.25
0.35 (10)
N
0.13
0.21
0.32
0.39
0.42
0.51
(F)
0.18
0.30
0.53
0.71
0.79
1.02
0.70 (20)
N
0.23
0.38
0.60
0.75
0.80
0.97
(F)
0.33
0.56
1.02
1.37
1.53
2.00
1.41 (40)
N
0.42
0.72
1.16
1.45
1.56
1.90
(F)
0.61
1.06
1.98
2.69
3.00
3.94
5.29 (150)
N
1.46
2.60
4.23
5.33
5.74
7.01
(F)
2.16
3.86
7.30
9.93
11.11
14.63
