The vacuum relief valve is used to protect the tank from buckling under vacuum pressure conditions that are sometimes created during unloading or steam cleaning.  The vacuum relief valve is constructed entirely of stainless steel.  The valve body and stem are available in either grade 304 or 316 stainless.  The valve is mounted to the car with 2-1/2" NPT threads.  The vacuum relief valve is available in either a traditional 3/4 psi vacuum setting or a new 4 psi vacuum setting that is designed to reduce non-accident releases.  The rubber quad-seal for the vacuum relief valve is available in the following color coded materials:

The newest versions of the Vacuum Relief Valve, the Secure-Cap and Tri-Cap VRV, have weather covers that do not move up and down as the valves cycle.  This change was made based on customer comments and requests.  This innovation eliminates the ability to accidentally actuate the VRV. 

The Secure-Cap adds an additional level of protection by using tamper proof fasteners that eliminate the need for safety seals. 

Tri-Cap and Secure-Cap Valve Ordering Part Numbers

DESCRIPTION

BODY/STEM MATERIAL

PRESSURE SETTING

AAR APPROVAL

Vacuum Relief

304 SS

3/4 psi

E-077023

506981-01

507882-01

VITON "A"

BROWN

506981-02

507882-02

BUNA "N"

BLACK

506981-03

507882-03

EPDM FOOD GRADE

WHITE

506981-04

507882-04

NEOPRENE

RED

506981-05

507882-05

VITON "B"

BLACK

506981-06

507882-06

CERTIFIED DUPONT VITON "A"

BLACK

506981-07

507882-07

EPDM (BLACK)

BLACK

506981-08

507882-08

VITON 747

BLACK

506981-09

507882-09

NEOPRENE (WHITE FOOD GRADE)

WHITE

506981-10

507882-10

BUNA "N" (BLACK FOOD GRADE)

BLACK

506981-11

507882-11

VITON GF

BLACK

506981-12

507882-12

CS-4273B

BLACK

506981-13

507882-13

CS-5355

BLACK

506981-14

507882-14

VITON GF-S

BLACK

506981-15

507882-15

VITON EXTREME ETP

BLACK

506981-16

507882-16

CHEMRAZ 505

BLACK

506981-17

507882-17

KALREZ 4079

BLACK

506981-18

507882-18

RUBBER, FOOD GRADE

BLACK

Old Style Valve Ordering Part Numbers

(QUAD SEAL MATERIAL) *

VITON "A"

BUNA "N"

EPDM FOOD GRADE

NEOPRENE 

DESCRIPTION

BODY/STEM MATERIAL

PRESSURE SETTING

BROWN

BLACK

WHITE

RED

AAR APPROVAL

Vacuum Relief

304 SS

3/4 psi

098751-01

098751-02

098751-04

098751-03

E-077023

304 SS

4 psi

500845-01

500845-02

500845-04

500845-03

E-077023

316 SS

3/4 psi

500059-01

500059-02

500059-04

500059-03

E-077023

316 SS

4 psi

500824-01

500824-02

500824-04

500824-03

E-077023