Replacement o-rings for quick connect pressure sensors

How do I get replacements for the o-rings on my pressure sensor connections?

As a natural process of the aging of rubber, o-rings will eventually lose their elasticity and crack.  Replacement o-rings on quick-connect type pressure sensors, are size 006, 70 Durometer rubber.

These are our 638-021 part number but they are readily available through other vendors.  

While web pages may no longer exist for much older parts that use this o-ring, some of these items are listed below.

Part Number	Description
CI-6533	PRESS SNS 0-700KPA DIF
CI-6534	PRESS SNS 0-10KPA GA
TD-8592	SMALL PISTON HEAT ENGINE
PS-2133	PASPORT Respiration Rate Sensor