NIBCO Check Valve Bronze Swing - Manual (Page 4)

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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 the Class
125, 150, 200 and 300 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 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.
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 rendering it inoperable.