Frequently Asked Questions
Where should a vented valve be vented?
It should be vented immediately downstream of the reason a vented valve is needed. Vented PO checks need the same amount of pilot pressure to open as a non-vented valve but once open they require less than 100 psi of pilot pressure to stay open.
Study the two circuits below.
- In the one on the right, the load is free to move, the check is being held open by normal tank line pressure that is seen as pilot pressure. The circuit on the right may work correctly on start up and then fail when temperatures drop or return line filters get full.
- In the circuit on the left the vent connection nullifies the tank line pressure seen at the pilot connection. The result is zero effective pilot pressure.
