Masoneilan 174-7 Low Pressure Relief Regulator
Overview
The Masoneilan 174-7 is the relieving model of the Masoneilan 174 Series from Baker Hughes. In the catalogue numbering the first digit after the series is the action, with 1 for reducing and 7 for relieving, and the 174-7 is therefore the member of the family that opens to relieve pressure above its set point instead of reducing a supply. It works at very low pressure: Baker Hughes limits the maximum pressure for the Masoneilan 174-7 to 4.4 psig (0.3 barg) and gives set points from 1.4 inches of water column to 4.4 psig. That makes it a small, self-acting protective device for tank blanketing systems, gas holders and low pressure headers.
Seven Star LLC, a trusted Masoneilan supplier for Oman and the GCC, supplies the Masoneilan 174-7 to utilities, tank farm operators and process-skid builders. The Muscat instrumentation division confirms spring type and nozzle against the relief set pressure and the flow to be passed, and provides the Baker Hughes technical specification for the unit you order.
Relieving Operation of the Masoneilan 174-7
The Masoneilan 174-7 uses the same body, large diaphragm and lever as the 174-1, but it is applied to relieve. The set pressure is determined by the spring, and as the sensed pressure rises above the set point the diaphragm moves against the spring and the lever opens the seat so that the excess gas can pass. As the pressure drops back the spring and lever close the disc and the regulator reseals. Baker Hughes tabulates an offset from the set point for each spring: 0.4 inches w.c. (1 mbar) for UBB02, 0.8 (2 mbar) for UBB03, 2 (5 mbar) for UBB05, 3.15 (8 mbar) for UBB06, 6.8 (17 mbar) for UBB07, 10.24 (26 mbar) for UBB08, 0.73 psig (50 mbar) for UBB09 and 1.12 psig (77 mbar) for UBB10.
Because the large diaphragm responds to pressure changes of a few millibar, the Masoneilan 174-7 can protect equipment that would be damaged by even a modest overpressure, such as atmospheric storage tanks and thin-walled vessels. The regulator is not a certified safety valve, and Baker Hughes lists it among direct-operated regulators for relief applications; where a code-rated safety device is mandated, our team can quote an approved relief valve instead.
Engineering Design of the Masoneilan 174-7
The construction of the Masoneilan 174-7 matches the reducing model: a carbon steel body and cases, a 316 stainless steel seat and stem, a nitrile (NBR) disc and diaphragm, a PTFE guide bushing and a chrome-vanadium steel spring, with stainless steel available on request. Eight springs, UBB02, UBB03, UBB05, UBB06, UBB07, UBB08, UBB09 and UBB10, cover the pressure range up to 4.4 psig, and the body can be turned to four positions relative to the spring case. Sizes run from 1/2 inch to 1-1/2 inch (DN15 to DN40) with NPT or GAS threads, and the temperature limit is -0.4 to 194°F (-18 to 90°C).
Fifteen nozzles are available, from 1 to 15. On the relief version the rated Cv rises from 0.04 at nozzle 1 to 0.17 at nozzle 2, 0.75 at nozzle 4, 2.50 at nozzle 8 and 3.95 at nozzle 12, and reaches 4.86 on 3/4 inch and 4.90 on 1 and 1-1/2 inch bodies at nozzle 15. The 1/2 inch body is offered with nozzles 1 to 12 only.
Key Features
The Masoneilan 174-7 is selected for low pressure relief duty for these reasons:
- Relief set points from 1.4 inches w.c. to 4.4 psig cover blanketing and gas holder protection.
- The large diaphragm area detects small pressure changes accurately at low settings.
- Lever design provides reliable reseating after relief.
- Eight spring types give a fine choice of set pressure, each with a published offset.
- Fifteen nozzles let the relieving capacity be matched from a trickle to several thousand SCFH.
- Four body orientations ease installation on tank nozzles and small headers.
- Diaphragm, seat and spring can be serviced in line.
- Internal pressure sensing and no need for any auxiliary power or air supply.
Industrial Applications
The Masoneilan 174-7 is applied on nitrogen-blanketed storage tanks, day tanks and chemical vessels, on biogas and digester gas lines, on low pressure fuel gas headers and on laboratory gas manifolds where the pressure must never exceed a few millibar above the set point. In Oman these services occur in fuel storage and terminal facilities at Sohar, Duqm and Salalah, in wastewater and sludge treatment plants, and in industrial gas distribution to factories.
In Oman and the GCC, Seven Star LLC supplies the Masoneilan 174-7 with the family page for the Masoneilan 174 Series regulator, so a blanketing system can be supplied with a 174-1 reducing regulator and a 174-7 relieving regulator from one source.
Technical Specifications
The table below summarises the Masoneilan 174-7 data from the Baker Hughes technical specification. Capacities are taken from the relief capacity table.
| Parameter | Specification |
|---|---|
| Model | Masoneilan 174-7 (relieving action, elastomeric diaphragm) |
| Sizes and ends | NPT or GAS threaded bodies, DN15 to DN40 (1/2, 3/4, 1 and 1-1/2 in.) |
| Maximum pressure | 4.4 psig (0.3 barg) |
| Set pressure range | 1.4 inches w.c. through 4.4 psig |
| Spring types | UBB02, UBB03, UBB05, UBB06, UBB07, UBB08, UBB09, UBB10 |
| Temperature range | Minimum -0.4°F (-18°C), maximum 194°F (90°C) |
| Weight | 30 lb (13.5 kg) |
| Rated Cv, nozzle 2 / 4 / 8 / 12 / 15 | 0.17 / 0.75 / 2.50 / 3.95 / 4.86 to 4.90; nozzle 9 is 2.96 (the 1/2 in. cell is misprinted 1.96) |
| Capacity, UBB02 at 1.4 in. w.c. | 1.14 SCFH with 1 mm orifice; 31.48 SCFH with 4 mm; 213.41 SCFH (5.718 Nm3/h) with 14 mm |
| Capacity, UBB09 at 2.8 psig | 14.19 SCFH with 1 mm orifice; 285.31 SCFH with 4 mm; 1673.81 SCFH (44.844 Nm3/h) with 14 mm |
| Capacity, UBB10 at 4.4 psig | 19.07 SCFH with 1 mm orifice; 360.99 SCFH with 4 mm; 2117.81 SCFH (56.739 Nm3/h) with 14 mm |
One printing error needs flagging in the relief Cv table (Table 6): the 1/2 inch body at nozzle 9 shows 1.96, whereas the 3/4, 1 and 1-1/2 inch bodies all show 2.96 and the values climb steadily from 2.50 at nozzle 8 to 3.40 at nozzle 10. The value for the 1/2 inch body is evidently 2.96, and Seven Star LLC quotes it that way while confirming against the current Baker Hughes revision. The pressure-heading error in the same document’s reducing capacity table is explained on the Masoneilan 174-1 page.
Related Masoneilan regulators include the Masoneilan 174-1 low pressure reducing regulator, Masoneilan 171 Series pressure reducing regulator and Masoneilan 173 Series back pressure regulator.
Request a Quote for Masoneilan 174-7
Send an RFQ for the Masoneilan 174-7 to the Seven Star LLC instrumentation division stating the gas, the relief set pressure, the flow to be relieved and the connection size. We confirm spring type and nozzle, report regional availability, and supply the Masoneilan 174-7 datasheet from Baker Hughes for download from this page. Seven Star LLC supplies genuine Masoneilan products across Oman and the GCC.
- Datasheet Masoneilan 174 Series Regulators Technical Specifications Datasheet Download
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