Pressure Protection Valves Compared
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The inlet (supply side) of a protection valve is normally closed and does not open until pressure at the supply side, usually in a reservoir, reaches an opening threshold. This serves to allow a build up of air pressure in the system before it is allowed to become available to an accessory such as an air suspension. When the pressure on the supply side falls the valve closes to preserve some amount of air pressure on the delivery side of the valve. When a check valve is included in the design, the check valve will not allow air pressure on the delivery side of the valve to fall to any extent when the pressure at the supply side falls. For this reason the check valve feature is used between two air reservoirs to protect the second reservoir from any decrease in pressure.
From the list below you can see that there is a wide range of opening and closing thresholds. The Bendix PR-2 specifies an opening threshold that is “15-20 psi higher” than the closing pressure. The PR-4 style has an opening threshold 10 psi higher than the closing. The Bendix valves all include mounting holes so that direct attachment to a reservoir is not necessary.  Example of Haldex 90554107 direclty connected to reservoir. |
 Sealco pn 140270 pressure protection valve with internal check valve & single mounting hole  Haldex pn 90554107  Bendix PR-4 pressure protection valve pn 286500N |
Pressure Protection Valves In Stock
| | PN | Delivery port | Supply port | Style | Open psi | Close psi | Mntng holes |
| Sealco | 140280 | 3/8" | 3/8" | ck valve | 70 | 1 |
| Sealco | 140270 | 3/8" | 3/8" | ck valve | 60 | 1 |
| Haldex | KN31000 | 1/4" | 1/4" | 65 | 56 | na |
| Haldex | 90554107 | 1/4" | 1/4" | 75 | 70 | na |
| Haldex | KN31170 | 1/2" male | 3/8" female | Inline | 50 | ck valve | na |
| Bendix | 277227N | 1/4" | 1/4" | PR-2 | 90* | 75 | 2 |
| Bendix | 277148N | 1/4" | 1/4" | PR-2 | 100* | 85 | 2 |
| Bendix | 277147N | PR-2 |
| Bendix | OR277147X | 1/4" | 1/4" | PR-2 | 80* | 65 | 2 |
| Bendix | 286500N | 1/4" | 1/4" | PR-4 | 95* | 85 | 2 |
A pressure protection valve mounted at air tank safeguards air supply in tank in this simple example of four air springs controlled by a single leveling valve.
