Thomas & Betts UDAS, UDAP Gas Piping and Pressures, Sizing Gas Supply Line, Gas Connection Size

12.Gas Piping and Pressures

WARNING: This appliance is equipped for a maximum gas supply pressure of 1/2 pound, 8 ounces, or 14 inches water column. Supply pressure higher than 1/2 pound requires installation of an additional lockup-type service regulator external to the unit.

WARNING: PRESSURE TESTING SUPPLY PIPING

Sizing

Gas

Supply

Line

Test Pressures Above 1/2 PSI: Disconnect the heater and manual valve from the gas supply line which is to be tested. Cap or plug the supply line.

Test Pressures Below 1/2 PSI: Before testing, close the manual valve on the heater.

Capacity of Piping

						Cubic Feet per Hour based on 0.3" w.c. Pressure Drop
				Specific Gravity for Natural Gas -- 0.6							(Natural Gas -- 1000 BTU/Cubic Ft)
				Specific Gravity for Propane Gas -- 1.6							(Propane Gas -- 2550 BTU/Cubic Ft)
Length										Diameter of Pipe
of		1/2"				3/4"			1"			1-1/4"			1-1/2"				2"
Pipe	Natural		Propane		Natural		Propane	Natural		Propane		Natural	Propane	Natural		Propane		Natural		Propane
20’	92		56		190		116	350		214		730	445		1100		671	2100		1281
30’	73		45		152		93	285		174		590	360		890		543	1650		1007
40’	63		38		130		79	245		149		500	305		760		464	1450		885
50’	56		34		115		70	215		131		440	268		670		409	1270		775
60’	50		31		105		64	195		119		400	244		610		372	1105		674
70’	46		28		96		59	180		110		370	226		560		342	1050		641
80’	43		26		90		55	170		104		350	214		530		323	990		604
90’	40		24		84		51	160		98		320	195		490		299	930		567
100’	38		23		79		48	150		92		305	186		460		281	870		531
125’	34		21		72		44	130		79		275	168		410		250	780		476
150’	31		19		64		39	120		73		250	153		380		232	710		433
175’	28		17		59		36	110		67		225	137		350		214	650		397
200’	26		16		55		34	100		61		210	128		320		195	610		372
	Note: When sizing supply lines, consider possibilities of future expansion and increased requirements.
				Refer to National Fuel Gas Code for additional information on line sizing.

WARNING: All components of a gas supply system must be leak tested prior to placing equipment in service. NEVER TEST FOR LEAKS WITH AN OPEN FLAME. Failure to comply could result in personal injury, property damage or death.

Gas Connection Size

All piping must be in accordance with requirements outlined in the National Fuel Gas Code ANSI/Z223.1a (latest edition) or CAN/CGA-B149.1 and B149.2 (See Paragraph 2). Gas supply piping installation should conform with good practice and with local codes. Support gas piping with pipe hangers, metal strapping, or other suitable material; do not rely on the heater to support the gas pipe.

The heater is orificed for operation with natural gas having a heating value of 1000 (± 50) BTUH per cubic ft or propane gas with a heating value of 2500 (± 100) BTUH per cubic ft. If the gas at the installation does not meet these specifications, consult the factory for proper orificing.

Pipe joint compounds (pipe dope) shall be resistant to the action of liquefied petro- leum gas or any other chemical constituents of the gas being supplied.

Install a ground joint union and manual shutoff valve upstream of the unit control system, as shown in FIGURE 10. Installation of a trap with a minimum 3" (76mm) drip leg is required.

The unit is equipped with a nipple that extends outside the cabinet. The gas con- nection is either 1/2” or 3/4”.

Gas Connection (inches)

30

45

60

75

100

125

150

175

200

225

250

300

350

400

Natural

1/2

1/2

1/2

1/2

1/2

1/2

1/2

1/2

1/2

3/4

3/4

3/4

3/4

3/4

Propane

1/2

1/2

1/2

1/2

1/2

1/2

1/2

1/2

1/2

3/4

3/4

3/4

3/4

3/4

Form RZ-NA I-UDA, P/N 195673 Rev 5, Page 12