should be disassembled and inspected In the following
should be tight when the valve is in open position.
e. Steam Couplers
. If steam blows
at the joint,
(1) Remove the strainer and disassemble the
may indicate broken lugs, faulty gasket, gasket spring, or
trap. Examine the spring seat, disk, diaphragm, and
Replace entire coupling only when
strainer. Replace any defective parts.
(2) Test diaphragms before installation. If
the diaphragm is expanded too much, it will not return to
f. Constant Pressure Valve (fig 11-5). This valve
its normal fully contracted form when cool. Place the
should be removed and repaired annually using
diaphragm in a holding fixture and submerge in water at
procedures as follows:
about 190 . Any leaks will be indicated by rising
(1) Disassemble the valve, clean and inspect
bubbles. A leaky diaphragm must be discarded; no
parts for wear.
attempt will be made to refill or repair it. After the test,
(2) Replace any part showing excessive wear
submerge the diaphragm in cold water to contract it, then
on any springs that have lost their tension.
remove it from the holding fixture.
(3) Inspect the diaphragm carefully,
(3) Reassemble the trap. Check to see the
particularly at the edges where continual flexing occurs,
adjusting screw, pins, and cotters are in good condition.
as cracks develop in these areas.
Test the trap on a steam line at about 55 psi. Regulate
(4) Check the needle valve assembly, assure
the adjusting screw and observe for excessive steam
that the stem is true, and the valve and seat are not
(5) Replace the needle valve if it or the valve
i. Flow Limit Valve (fig 11-4). These valves should
seat are scored or wiredrawn.
be checked and repaired annually, prior to the heating
(6) Reassemble, adjust, and test the constant-
season, using the following procedure:
pressure valve under live steam pressure.
(1) Disassemble the valve and inspect the
g. Vapor Regulator (fig 11-4). Visual observation
inlet valve assembly.
of vapor regulators is sufficient to insure proper
(2) Thoroughly clean the inlet valve
functioning. Steam leaking through the regulator when
assembly, particularly the strainer. Assure that the stem
the vapor valve is closed is an indication the valve is not
is free and that the valve and seat are not seated or worn.
seating properly. A worn valve seat or dirt between the
(3) If the inlet valve will not seat tightly,
valve and seat may cause this condition. A worn seat
replace the inlet valve assembly and inspect the 'gasket
should be reground or replaced; dirt may be blown out by
under the cap to see that the body of the flow limit valve
closing the shutoff valve ahead of the regulator for a few
minutes, then opening it again. If steam blows from the
(4) Reassemble the valve and put it on a
drain tube, the bellows diaphragm may be damaged.
low-pressure steam line to determine the pressure at
Before each heating season the regulator should be
which the valve opens.
tested under pressure. Assure that the operating rods are
(5) If it does not open at the correct pressure,
free in the guide ruts. Thorough biennial overhaul
replace the spring.
includes the following:
j. Vapor Retarder (fig 11-4).
A steam blow from the
(1) Disassemble, clean, and inspect all parts
outer drain tube of a regulator indicates a faulty vapor
Vapor retarders should be disassembled,
(2) Replace badly worn or damaged parts.
cleaned, and inspected at least every 2 years, as follows:
(3) Check spring tension and inspect the
(1) Test the thermostatic bellows for leaks by
placing it in a holding fixture and submerging in boiling
(4) Inspect the regulator valve, assembly,
water. Do not submerge except in a fixture, as an over-
bellows packing assembly, and the main bellows.
expanded bellows will not return to its normally fully
(5) Reassemble the regulator and check on a
contracted form. Leaks in the bellows will be indicated by
bubbles rising In the water. Leaky bellows must be
discarded and replaced.
h. Steam Traps. Excessive steam blows may be
(2) Contract the bellows by submerging in
eliminated by changing the position of the adjusting
cold water. Reassemble the vapor retarder; assure that
screw. A steam trap that cannot be properly adjusted
the cap is steamtight. If the retarder is fitted