Type of check valves needed for vacuum pump

[DaveB]

I need to add a couple of check valves on a dairy releaser that I'm using. I need one for the vacuum line, one for output when the vacuum is shut off and one for the sap input line. Do I need spring loaded check valves or check valves without springs? If it's the ones without springs, where do I find those? I can only find spring loaded ones. My concern was that the springs might not allow a proper flow, particularly on the sap input line.

[Clinkis]

Normally want to use a swing or gate check valve. They have no springs and give you the best flow. CDL sells them. I got mine from noble trade a plumbing supplier.

[wiam]

http://www.webbsonline.com/Item/PVC-Swing-Check-Valves-70374?gclid=CJCE3Zjh_bYCFQSCQgodnzwAnw