Introduction
The Model 121 Regulator represents a combination of capacity,
performance and value... Streamlined body passages provide large
capacity. An external control line is required from lower case to
control piping. The 121 has a fast speed of response, yet is stable
in operation. Soft seats assure positive tight shutoff. Orifices are
replaceable. Springs are color coded. It is also available as
a zero governor or atmospheric regulator, a relief valve or
backpressure regulator, and a vacuum regulator or vacuum breaker.
Installation
1. Examine the regulator for shipping damage.
2. Check nameplate data. Be sure regulator conforms with what
was ordered.
3. Inside of regulator and piping must be clean and free of dirt.
Remove all dirt and debris before installing regulator. Failure to
remove dirt/debris could result in regulator damage or trouble.
4. Remove all shipping screens and covers from the regulator. Do
not let dirt get inside the regulator.
5. Install the regulator. Make sure the inlet and outlet are correctly
connected. High pressure connects to the inlet. The flow arrow
must point downstream.
6. Screwed connections must conform with good piping practice
free of excess thread engagement per ANSI B2.1. Apply pipe joint
compound to male threads only.
7. The model 121 Regulator is usually right side-up as shown on the
Typical Installation drawing (See Page 3.) It may, however, be
installed upside down. When inverted it may be necessary to
readjust the set -point.
Caution: Do not install sideways.
The diaphragm should be horizontal.
8. On indoor installations requiring venting outdoors, run the vent
piping as short and direct as possible with minimum bends and
elbows. Use the same size or larger pipe as the vent connections
on the regulator. With natural gas, or any other hazardous gas,
vent to a safe place outdoors in case gas should accidentally be
discharged. Screen and protect the opening outdoors to guard
against water, ice, dirt, debris or insects. Install the control line.
Connect it into the outlet piping at least 5 pipe diameters
downstream from the regulator.
Cautions:
a. On backpressure regulators and relief valves the external
control line connects into the inlet piping, 5 pipe
diameters upstream from the regulator.
b. Do not install any automatic shutoff device that closes
completely between the regulator and the control line
connection into the piping.
To avoid excessive turbulence, the connection should be clean
and smooth on the inside and be located in straight pipe clear of
valves and fittings. Keep the inside of the control line clean and
protect it from corrosion. Pitch it away from the regulator and
avoid moisture pockets. It must be strong (1/4" for 121-8 and
121-12, 1/2" for 121-16, or larger steel tubing or pipe is
preferred). It must be well protected against breakage.
Regulator will open wide if the control line breaks.
9. Make sure the regulator is correctly connected and adequately
supported. Ensure all pipe joints are tight.
Start-Up
AThe inlet and outlet shutoff valves should both be closed.
If a by-pass is used, the by-pass valve should also be closed.
BNote the set-point (set-point is the outlet pressure the regulator is
adjusted to deliver). Regulator is factory adjusted to the set-point
specified on the order.
Caution: This caution applies where the piping downstream of
the outlet shutoff valve is pressured. That pressure must not
exceed the regulator set-point by more than the pressure
noted (see “Maximum Emergency Pressures”, Page 19).
CSlowly and carefully open the inlet shutoff valve just enough
to allow inlet pressure to build up slowly in the regulator
until it is fully pressured.
Caution: During start-up a pressure gauge must be used
on the regulator outlet pressure and carefully watched.
While inlet pressure builds up, outlet pressure must not
exceed set-point by more than 1 psi. If outlet pressure begins
to exceed set-point by more than 1 psi, close the inlet shutoff
valve. This indicates the regulator is not closing properly.
Check and make necessary corrections before proceeding
with start-up. If regulator outlet pressure exceeds set-point
by more than the pressure noted, refer to “Maximum
Emergency Pressures”, Page 19 for instructions.
DCheck installation for leaks.
ESlowly open the outlet shutoff valve to allow a small flow
(approximately 1000 SCFH). Make sure the flow of gas does
not create a hazard.
Note: If piping downstream of outlet shutoff valve is pressured,
see “CAUTION” under B.
FWith gas flowing, check for correct inlet and outlet pressures.
It may be necessary to further open the inlet shutoff valve to
maintain full inlet pressure.
GMake sure the regulator closes tight (tight lock-up). To do this,
reduce flow to zero by slowly closing the outlet shutoff valve.
Outlet pressure should not exceed set-point by more than 6" w.c.
HFully open inlet and outlet shutoff valves. Do this slowly and
carefully. Watch pressure gauges.
IComplete start-up by making sure there are no leaks.
NOTE
Do not exceed the regulator's pressure ratings. The regulator outlet
has a lower pressure rating than the inlet. Do not expose the
regulator outlet or control line to inlet pressure.
Regulator with external control may be used as an upstream
monitor or upstream regulator in a monitor set. The control
line must connect into the outlet piping downstream of the
downstream regulator.
If the regulator is to be moved to another location, make sure its
construction is compatible with the pressure and flow conditions.
2
Installation and Maintenance
Model 121 Regulators
