Grain Systems PNEG-526 - Manual (Page 169)

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 (remember...regulators
open wide if the control line breaks).
9. Make sure the regulator is correctly connected and
adequately supported and pipe joints are tight.
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.
And it is also available as a zero governor or atmospheric regula-
tor, a differential regulator, a relief valve or backpressure regula-
tor, 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 dam-
age or trouble.
4. Remove all shipping screens and covers from the regula-
tor. 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 prac-
tice 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 2). It may,
however, be installed upside down. Although, 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.
Regulator Installation and
Maintenance Instructions
Model 121
Regulators
Start-Up
A. The inlet and outlet shutoff valves should both be closed. If a
by-pass is used, the by-pass valve should also be closed.
B. Note the set-point (set-point is the outlet pressure the regula-
tor 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 pres-
sure must not exceed the regulator set-point by
more than the pressure noted (see “Maximum
Emergency Pressures”, Page 18).
C. Slowly 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 pro-
ceeding with start-up.
If regulator outlet pressure exceeds set-point by
more than the pressure noted, refer to “Maximum
Emergency Pressures”, Page 18 for instructions.
D. Check installation for leaks.
E. Slowly open the outlet shutoff valve to allow a small flow (ap-
proximately 1000 SCFH). Make sure the flow of gas does
not create a hazard.
NOTE: If piping downstream of outlet shutoff valve is pres-
sured, see “CAUTION” under B.
F. With 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.
G. Make 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.
H. Fully open inlet and outlet shutoff valves. Do this slowly and
carefully. Watch pressure gauges.
I. Complete start-up by making sure there are no leaks.
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.
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 pip-
ing downstream of the downstream regulator.
• If the regulator is to be moved to another location,
make sure its construction is compatible with the pres-
sure and flow conditions.
Temperature Limits
The Model 121 Regulator can be used for flowing temperatures
from –20°F to 150°F.
Buried Service
The Model 121 Regulator is not recommended for buried service.
RM-1328 Rev. 9