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G. PRODUCTION TEST PROCEDURES
Valves are pneumatically shell tested and seat tested at a pressure of 80 psi in
accordance with Federal Specifications and MSS SP-80 and/or MSS SP-139
Manufacturers Standardization Society requirements.
H. PRINCIPAL DIMENSIONS
Principal dimensions of the valve are specified in the appropriate catalog.
1.3 DETAILED DESCRIPTION
The bronze check valves listed above and covered in these instructions are bronze valves
made of ASTM B62 material for Class 125 and 150 valves and from ASTM B61 material
for Class 200 and 300 valves.
The Lead-Free* Performance Bronze
®
swing check valves listed above and covered in
these instructions are made from UNS Alloy C87850.
Check valves are used in systems which allow flow to move freely in the direction of the
arrow cast onto the side of the valve body, however, should flow reversal occur, the disc
in the valve will go to the closed position and not allow flow to reverse. The primary function
of a check valve is to prevent backflow.
The disc is centered over the seat in the valve by means of a hanger which is hinged by
means of a pin to the main valve body. Therefore, any movement of the disc is in a true
arc and the disc will always center itself over the seat in the valve body. On NIBCO bronze
check valves, no control of the disc can be affected from the exterior of the valve body.
Lever and weights are available only on NIBCO iron check valves.
The body and bonnet are held together by threads of the male and female type; male
threads being on the bonnet section and female threads being within the body. There are
no gaskets between the body and bonnet to affect seals. This is strictly a metal-to-metal
seal as required by standards. This general arrangement is used on all of the listed swing
check valves.
2.0 INSTALLATION
2.1 PRELIMINARY INFORMATION
The bronze check valves may be installed in both horizontal and vertical lines with upward
flow or in an intermediate position. They will operate satisfactory in a declining plane no
more than 15°. Under no circumstances should the valve be installed in a horizontal line
with the bonnet facing in the vertical down position, this will not only trap fluids, but it will
not allow the valve to function in the check position.
NIBCO recommends that check valves should not generally be used in close proximity to
reciprocating pumps and compressors. The constantly fluctuating pressure curve passes
pulsations to the moving parts of the valve and severely shortens the life of the valve due
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