Appendix A: Check Valve/Air Purge Screw Operation - Veeder-Root Red Jacket Quick-Set Installation, Operation And Service

Appendix A: Check Valve/Air Purge Screw Operation

This appendix discusses the theory of operation of the Red Jacket STP's check valve and air purge screw.
Check Valve Operation
Pump On
As shown in the check valve cutaway diagram in Figure A-1, when the pump is On, the check valve is opened by
fuel flow.
Pump Off
When the pump shuts off, the check valve reseats isolating the line. As pressure in the line builds due to thermal
expansion, the excess pressure vents through the relief valve back into the tank as shown in Figure A-2.
Spring
Check valve
From pump
Figure A-1. Pump On condition
Relief valve
Check valve
To Tank
Figure A-2. Relief valve vents excess line pressure
A-1
To line
rjpumps\ckvlv1
Excess line
pressure
rjpumps\ckvlv2