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SECTION 2
EDRP-IOM-2019-0212
ƒ Line Gas Pressure Regulation
When inlet gas pressure exceeds the maximum on the
boiler name plate, a line gas pressure regulator is required
to step the gas pressure down to an acceptable pressure.
See Figure 9.
Proper selection and installation of a gas pressure regulator
is essential in providing ideal conditions for efficient and
reliable combustion. Adhere to the following guidelines
when selecting and installing a gas pressure regulator:
A sediment trap is recommended prior to the inlet of
ƒ
the regulator.
If the level of pipe system cleanliness is unacceptable
ƒ
or unknown, install a gas filter prior to the regulator.
On the outlet of the regulator: Install a straight and
ƒ
uninterrupted section of pipe matching regulator
connection size with a minimum length of 10 pipe
diameters prior to any valves or fittings.
When installed in close proximity to an appliance,
ƒ
some regulators may experience oscillation (hunting)
or an outlet pressure spike when demand ends.
Provide adequate volume by locating the regulator
a minimum of 10 total linear feet of pipe from boiler
fuel train inlet. Consult the regulator manufacturer for
installation requirements.
The body size should never be larger than the pipe
ƒ
size. However, a properly sized regulator may be
smaller than the pipeline.
The inlet pressure used for sizing should be measured
ƒ
directly at the regulator inlet. Measurements taken at
any other point may be subject to losses associated
with upstream piping.
Nominal
ID
Pipe Size
Inch (mm)
Inch (mm)
1-1/4 (31.75)
1.380 (35.05)
1-1/2 (38.1)
1.610 (40.89)
2 (50.8)
2.067 (52.50)
2-1/2 (63.5)
2.469 (62.71)
3 (76.2)
3.068 (77.92)
4 (101.6)
4.026 (102.26)
6 (152.4)
6.07 (154.17)
8 (203.2)
7.98 (202.69)
Questions? Please Contact Your Local Manufacturer's Representative
TABLE 3 - SCH 40 PIPE NATURAL GAS CAPACITY
Equivalent Pipe Length
Max Capacity in ft3 of natural gas per hour at 14" WC pressure.
Pressure drop of 0.5" WC. Equivalent length of pipe (feet)
90 Elb
Tee
20
Feet
Feet
(meter)
(meter)
3.45 (1.05)
6.9 (2.10)
950
4.02 (1.22)
8.04 (2.45)
1460
5.17 (1.57)
10.3 (3.13)
2750
6.16 (1.87)
12.3 (3.74)
4350
7.67 (2.33)
15.3 (4.66)
7700
10.10 (3.07) 20.2 (6.15)
15800
10.10 (3.07) 23.60 (7.19) -----
13.30 (4.05) 29.10 (8.86) -----
Consult the regulator manufacturer for orifice selection.
ƒ
If two or more springs are available for a particular
ƒ
outlet pressure in the desired range use the spring with
the lower range for better accuracy.
NOTEE:
Regulators are not intended for use as "shut off"
–
devices. As per ANSI Z21.80/CSA 6.22 lock-up is defined as an
outlet pressure not more than 150% or 5" W.C., whichever is
greater, above the setpoint after a downstream safety shutoff
valve closes within 2 seconds.
Appliance regulators must not be used as line gas
ƒ
pressure regulators to step down the gas pressure.
For additional information regarding gas regulator
selection and installation consult your regulator
manufacturer, any applicable local codes or ordinances,
the standard for line pressure regulators ANSI Z21.80/
CSA 6.22, and The National Fuel Gas Code NFPA 54/ANSI
Z223.1.
ƒ Gas Piping Installation
Adhere to the following for gas piping installation:
1. See Table 3 for required natural gas pipe size, based on
overall length of pipe from the meter plus equivalent
length of all fittings. Approximate sizing may be based
on 1,020 BTU for 1 cubic foot of natural gas. See Figures
6 and 7 for piping arrangements.
2. Install a manual gas shutoff valve prior to the boiler.
3. Piping must be installed such that no piping stresses
are transmitted to the boiler. The boiler cannot be used
as a pipe anchor.
40
60
80
-----
-----
-----
990
810
-----
1900
1520
1300
3000
2400
2050
5300
4300
3700
10900
8800
7500
-----
-----
-----
-----
-----
-----
INSTALLATION
100
150
200
-----
-----
-----
-----
-----
-----
1150
950
800
1850
1500
1280
3250
2650
2280
6700
5500
4600
20200
16503
12766
41200
33660
29128
2-13
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