NIBCO Technical Services • Phone: 1.888.446.4226 • Fax: 1.888.336.4226
5
to wear and causes premature failure. Loose parts can also be passed down the line which
would compound the problem. Screw type and centrifugal pumps and compressors that
deliver a constant pressure curve do not have this problem. In some carefully designed
systems check valve have been used successfully by incorporating surge tanks, hammer
arrestors and other piping modifications with the valve placed downstream from the pump.
The ultimate decision for fitness of use however lies in the hand of the end user and his
piping designer.
NOTE: Check valves should never be installed immediately adjacent to a pump discharge
or change in direction. Check Valves should be installed downstream from all sources of
line turbulence, including fittings and valves, at a minimum of 5x the nominal pipe diameter
(preferably 10x) with straight piping to provide laminar flow.
All NIBCO check valves are shipped in cardboard boxes for protection against exterior
damage and accumulation of dust or dirt on the delicate seating surfaces. The boxes are
not waterproof and, therefore, require that they be protected from the weather.
2.2 HANDLING AND INSTALLATION
Each valve should be handled very carefully and not dropped or exposed to a dirty
environment before it is assembled into the system. Under no circumstances should the
valve be installed into the line by wrenching through the valve body, this means that when
a valve is being threaded onto a pipe, the wrench should be on the end where the joint is
being made.
It is very important to make certain that the threads of the pipe are clean at all times and
machined properly. When improperly tapered pipe is screwed into the female valve
threads, the pipe can be screwed so deep that it can ruin the seats of the valve. Care
should also be used to assure that the valve is not over tightened because the steel pipe
is much stronger that the bronze material, therefore, the bronze will distort and cause valve
malfunction or leakage at the joint. When screwing the valve onto the pipe, the disc should
remain in the closed position if possible.
On solder end type valves it is necessary to make sure that the valve disc is in the open
position while it is being heated for soldering into the line. The major caution here is that
the valve not be overheated and that the proper amount of solder is used so that it does
not flow into the valve, fouling the seat or damaging the disc, rendering it inoperable.
Attached to this manual, in the Appendix, are proper general instructions for soldering, brazing
and threading installation of valves. For lead-free solderability information, see NIBCO Technical
Bulletin NTB-0910 Lead-Free* Silicon Bronze Alloys Soldering & Brazing Recommendations
For soldering or threading, the recommended best practice is to remove the bonnet and
disassemble the hanger assembly from the valve; for brazing installation it is mandatory
that the hanger assembly be removed prior to assembly.
It is always essential that the bonnet be removed with great care. The necessary steps to
do this must be accomplished with a suitable wrench with flat jaws (do not use pipe
wrench). Use a properly sized wrench for the bonnet cap to loosen the bonnet. Generally
it is best to loosen the bonnet with a slight impact to the wrench. After the bonnet is
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