40
GTS HUMIDIFIER LX SERIES INSTALLATION, OPERATION, AND MAINTENANCE MANUAL
EXAMPLE
For this example, refer to the tables on Page 39.
To determine gas piping size, begin by calculating the cubic feet/hour (ft
3
/hr)
or m
3
/hr using the following formula:
• Btuh (kW) input / calorific value of gas
Calorific values are:
• Natural gas: 1025 Btu/ft
3
(10.6 kW-hr/m
3
)
• Propane: 2500 Btu/ft
3
(25.9 kW-hr/m
3
)
For example, if you have a LX-150 operating on natural gas, calculate the ft
3
/
hr or m
3
/hr as follows:
• 183,000 Btuh / 1025 Btu/ft
3
= 390 ft
3
per hour
• 117.2 kW / 10.6 kW-hr/m
3
= 11.1 m
3
per hour above your calculated
ft
3
/hr or m
3
/hr. In this example, you are looking for the next highest
value above 390 ft
3
/hr (11.05 m
3
/hr), which is 400 ft
3
/hr (11.3 m
3
/hr)
and indicates the use of a 1¼" (DN32) pipe for this application.
Using the same example, if the specific gravity of your natural gas was 0.55
(instead of the 0.60 standard), see Table 39-2 for an adjustment factor.
In this case, the factor would be 1.04, which you multiply by the 390 ft
3
/hr
(11.05 m
3
/hr) value. This gives you a new value of 406 ft
3
/hr (11.49 m
3
/hr).
Referring again to Table 39-2, you see that for the same 60 ft (18 m) length,
you now need to use 1½" (DN40) pipe due to the change in the specific
gravity of the gas.
Gas leak testing
• When leak-testing the gas supply piping
system, disconnect the humidifier and its gas
shutoff valve during any pressure in excess
of 24" wc (6 kPa). Isolate the humidifier from
the gas supply piping system by closing its
field-installed manual shutoff valve during
any pressure not equal to 24" wc (6 kPa).
• With the burner running at full capacity,
check gas supply pressure at the inlet
pressure tap of the combination gas control
valve.
For North American models, the
recommended supply pressure is 7" wc
(1.75 kPa) for natural gas or 11" wc (1.83
kPa) for LP gas. Perform gas piping purging
as described in ANSI Z223.1 (latest edition)
or in Canada, CAN/CGA-B149 codes. The
minimum supply pressure is 6" wc (1 kPa) for
natural gas or LP gas.
For European models, the required supply
pressure is 20 or 25 mbar for natural gas
and 30, 37, or 50 mbar for propane gas.
INSTALLATION
Gas (continued)
Piping:
