Watts 740 User Manual

ASME Water Pressure Relief Valves

For Pressure Protection of Hot Water Heating Boilers

Sizes:

⁄4" – 2" (20 - 50mm)

Series 174A

Bronze body safety relief valves for pressure protection only of all types of hot water heating boiler equipment. Pressure range 30 to 150psi (2 - 10 bar) with corresponding high ratings from 650,000 to 14,370,000 BTU/hr. Female inlet and outlet connections. Sizes

⁄4" - 2" (20 - 50mm).

Series 374A

Iron body with forged bronze inlet, 550,000 BTU/hr rating.

⁄4" (20mm) only.

Series 740

Iron body with expanded outlets for hot water space heating boilers. Pressure range 30 to 75psi (2 to 5 bar) with corresponding high ratings from 925,000 to 10,700,000 BTU/hr.

Features

• Seat located above drain; water can’t be trapped and sediment can’t foul seat.

• Non-mechanical seat-to-disc alignment will not stick or freeze.

• Water seal of high temperature resisting material isolates spring working parts from water during relief.

Specifications

Boiler Relief Valves

An ASME Section IV certified pressure relief valve shall be installed on each boiler as noted. The valve shall have a BTU rating in excess of the BTU rating of the boiler's heating output. Each hot water space heating boiler shall be equipped with a pressure relief valve set to relieve below the maximum boiler working pressure. The valve shall feature a raised seat and non-mechanical disc alignment. Working parts and spring shall be isolated from any discharge by a high temperature resistant material. Valve shall be a Watts Regulator Company Series 174A, 374A or 740.

Operation

As thermal expansion conditions develop, pressure builds up to the setting of the relief valve. This will cause discharging of small quantity of water.

Should operating controls fail, permitting runaway firing, the boiler water may reach steam temperatures. The valve will then open to discharge steam at the rate or faster than the boiler can generate it, thus restoring system pressure to a safer level.

Important: The discharge line must be the same size as the valve outlet, and must pitch downward from the valve to a safe place for disposal.

Valve lever must be tripped at least once a year to ensure that waterways are clear. This device is designed for emergency safety relief and shall not be used as an operating control.

For Hot Water Boiler Applications

ES-174A-740

Job Name

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Contractor

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Job Location

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Approval

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Engineer

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Contractor’s P.O. No.

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Approval

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Representative

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Watts product specifications in U.S. customary units and metric are approximate and are provided for reference only. For precise measurements, please contact Watts Technical Service. Watts reserves the right to change or modify product design, construction, specifications, or materials without prior notice and without incurring any obligation to make such changes and modifications on Watts products previously or subsequently sold.

Series 174A

Series 740

Series 174A, 374, 740

SERIES 174A

Set

⁄4" x 3⁄4" 1" x 1" 11⁄4" x 11⁄4" 11⁄2" x 11⁄2" 2" x 2" Pressure 20 x 20mm 25 x 25mm 32 x 32mm 40 x 40mm 50 x 50mm psi bar Model M3 Model M1 Model M1 Model M Model M

30 2.07 650,000 1,005,000 1,682,000 2,020,000 3,815,000 33 2.27 695,000 1,075,000 1,788,000 2,150,000 4,080,000 35 2.41 725,000 1,125,000 1,877,000 2,250,000 4,250,000 36 2.48 740,000 1,145,000 1,916,000 2,310,000 4,344,000 40 2.76 800,000 1,240,000 2,071,000 2,490,000 4,690,000 45 3.10 875,000 1,355,000 2,265,000 2,720,000 5,130,000 50 3.45 950,000 1,470,000 2,459,000 2,950,000 5,575,000 55 3.79 1,025,000 1,590,000 2,653,000 3,190,000 6,010,000 60 4.13 1,100,000 1,702,000 2,847,000 3,425,000 6,450,000 65 4.58 1,170,000 1,820,000 3,041,000 3,660,000 6,890,000 70 4.82 1,245,000 1,935,000 3,325,000 3,890,000 7,330,000 75 5.17 1,320,000 2,055,000 3,429,000 4,125,000 7,770,000 80 5.51 1,400,000 2,166,000 3,605,000 4,360,000 8,215,000 85 5.86 1,470,000 2,285,000 3,817,000 4,590,000 8,650,000 90 6.60 1,545,000 2,400,000 4,011,000 4,825,000 9,090,000

95 6.55 1,620,000 2,520,000 4,205,000 5,060,000 9,530,000 100 6.89 1,695,000 2,635,000 4,399,000 5,290,000 9,970,000 105 7.23 1,770,000 2,750,000 4,593,000 5,525,000 10,410,000 110 7.58 1,845,000 2,865,000 4,787,000 5,760,000 10,850,000 115 7.92 1,920,000 2,980,000 4,981,000 5,990,000 11,290,000 120 8.27 1,995,000 3,100,000 5,175,000 6,225,000 11,730,000 125 8.61 2,070,000 3,215,000 5,370,000 6,460,000 12,170,000 130 8.96 2,145,000 3,330,000 5,564,000 6,690,000 12,610,000 135 9.30 2,220,000 3,445,000 5,758,000 6,925,000 13,050,000 140 9.65 2,295,000 3,565,000 5,952,000 7,160,000 13,490,000 145 9.99 2,370,000 3,680,000 6,146,000 7,390,000 13,390,000 150 10.34 2,445,000 3,795,000 6,340,000 7,630,000 14,370,000

Capacity*

BTU/hr Steam Pressure Discharge Capacities

As tested and rated by the National Board of Boiler and Pressure Vessel Inspectors

Materials

Series 174A

• Bronze body construction

• Nonmetallic disc-to-metal seating

Series 740

• Iron body construction

• Nonmetallic disc-to-metal seating

Pressure – Temperature

Series 174A

Pressure range: 30psi to 150psi (2 to 10 bar) with corresponding high BTU/hr ratings from 650,000 to 14,370,000 BTU/hr. Maximum Temperature: 250ºF (121ºC)

Series. 374A

Pressure range: rated up to 550,000 BTU/hr at a 30psi (2 bar) setting only.

Series 740

Pressure range: 30psi to 75psi (2 to 5 bar) with corresponding high ratings from 925,000 to 10,700,000 BTU/hr. Maximum Temperature: 250ºF (121ºC)

Standards

Tested and rated by the National Board of Boiler and Pressure Vessel Inspectors to the requirements of ASME. Meets Military Spec. MIL-V-18634B, Type I, Class 3A, Style A (Bronze Body), Style B (Iron Body).

ASME

Dimensions – Weights

SERIES 174A

Size (Dn) Height Length Weight

Model in. mm Model in. mm in mm lbs. kg.

374A3⁄4 x 3⁄4 20 x 20 – 35⁄8 92 21⁄2 64 1.13 .5 174A3⁄4 x 3⁄4 20 x 20 M3 51⁄8 130 21⁄2 64 1.50 .7 174A 1 x 1 25 x 25 M1 53⁄4 146 3 76 3.13 1.4 174A 11⁄4 x 11⁄4 32 x 32 M1 83⁄8 213 43⁄4 121 6.25 2.8 174A 11⁄2 x 11⁄2 40 x 40 M 9 229 47⁄8 124 7.25 3.3 174A 2 x 2 50 x 50 M 115⁄8 295 61⁄4 159 13.75 6.2

SERIES 740

Set

⁄4" x 1" 1" x 11⁄4" 11⁄4" x 11⁄2" 11⁄2" x 2" 2" x 21⁄2" Pressure 20 x 20mm 25 x 25mm 32 x 32mm 40 x 40mm 50 x 50mm psi bar Model M1 Model M Model M Model M Model M

30 2.07 925,000 1,300,000 2,105,000 2,900,000 5,250,000 33 2.27 989,000 1,390,000 2,250,000 3,100,000 5,613,000 35 2.41 1,032,000 1,450,000 2,345,000 3,235,000 5,855,000 36 2.48 1,053,000 1,480,000 2,395,000 3,300,000 5,975,000 40 2.76 1,139,000 1,600,000 2,590,000 3,569,000 6,461,000 45 3.10 1,245,000 1,750,000 2,830,000 3,903,000 7,067,000 50 3.45 1,352,000 1,899,000 3,075,000 4,237,000 7,672,000 55 3.79 1,459,000 2,049,000 3,315,000 4,572,000 8,277,000 60 4.13 1,566,000 2,200,000 3,560,000 4,907,000 8,883,000 65 4.58 1,672,000 2,349,000 3,800,000 5,241,000 9,488,000 70 4.82 1,779,000 2,499,000 4,045,000 5,575,000 10,093,000 75 5.17 1,886,000 2,649,000 4,285,000 5,909,000 10,700,000

SERIES 740

7403⁄4 x 1 20 x 25 M1 55⁄8 143 3 76 1.88 9 740 1 x 11⁄4 25 x 32 M 71⁄4 184 31⁄2 89 3.13 1.4 740 11⁄4 x 11⁄2 32 x 40 M 83⁄4 222 45⁄8 117 6.13 2.8 740 11⁄2 x 2 40 x 50 M 91⁄4 235 51⁄4 133 7.50 3.4 740 2 x 21⁄2 50 x 65 M 115⁄8 295 63⁄4 171 16.50 7.5

USA: 815 Chestnut St., No. Andover, MA 01845-6098; www.watts.com

Canada: 5435 North Service Rd., Burlington, ONT. L7L 5H7; www.wattscanada.ca

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