Bulletin 71.1:912N April 2010 912N Series Pressure Regulators Introduction The 912N Series direct-operated, spring-loaded regulators are used in a variety of service and industrial applications. These regulators have limited-capacity internal relief across the diaphragm (see Figure 2) to help minimize overpressure. Any outlet pressure above the start-to-discharge point of the non-adjustable relief valve spring moves the diaphragm off the relief valve seat, allowing excess pressure to bleed out through the screened spring case vent. Inlet pressure capabilities are the same for all regulators described in this bulletin. However, outlet pressure ranges vary according to construction (see Table 1). Features   •  Accurate and Sensitive Control—Disk/lever assembly   is attached to a roller-style pivot for smoother action.   Handwheel construction is available for adjustment of   the pressure setting.   •  Versatility—These regulators are suitable for a   variety of gaseous fluids, including natural gas,   propane, and air. They are often used to supply   loading pressure to other units. P1024 Figure 1. 912N Series Regulator regulator spring   •  Weather and Insect Protection—“Drip lip” vent   helps resist blockage during icing conditions. When   the regulator is installed with the vent pointing down,   any ice that builds up forms a protective sheath   that helps keep the opening unobstructed. The vent   screen helps prevent foreign material from entering   the spring case and clogging or otherwise hindering   regulator operation. Relief Valve Spring pusher post assembly Relief Valve Seat vent screen diaphragm   •  Easy Maintenance—Diaphragm and disk/lever   assembly can be replaced without removing the   regulator from the pipeline. Principle of Operation M1021 Valve disk disk/lever assembly D100124X012 Body/Lower Refer to Figure 2. When downstream demand decreases, INLET PRESSURE Casing OUTLET PRESSURE ATMOSPHERIC PRESSURE the pressure under the diaphragm increases. This pressure Inlet PRESSURE INLETpressure overcomes the regulator setting (which is set by a spring). OUTLET PRESSURE OUTLETpressure Through the action of the pusher post assembly, the valve ATMOSPHERIC pressure ATMOSPHERIC PRESSURE disk moves closer to the orifice and reduces gas flow. If demand downstream increases, pressure under the diaphragm Figure 2. 912N Series Operational Schematic decreases. Spring force pushes the pusher post assembly (Standard Spring Case Vent Shown) www.fisherregulators.com

Bulletin 71.1:912N Specifications Available Constructions See Table 1 Pressure Registration Internal Body Sizes and End Connection Styles Inlet: 1/4 NPT Outlet: 1/4 or 3/8 NPT Maximum Allowable Inlet Pressure(1) 250 psig (17,2 bar) Spring Case Vent Standard Construction: 1/8 NPT tapped   with removable screen Standard Location Constructions Without Handwheel: Over body outlet Handwheel Constructions: Over body inlet Outlet Pressure Ranges(1) See Table 1 Approximate Weight 1.3 pounds (0,6 kg) Maximum Allowable Outlet Pressure(1) Emergency Outlet Pressure: 20 psig (1,4 bar) Recommended Outlet Pressure...

Table 1. Outlet Pressure Range Data Table 2. Capacities for Type 912N Regulators without Handwheel (Body Size 1/4 x 3/8 NPT) Table 3. Capacities for Type 912N Regulators with Handwheel (Body Size 1/4 x 3/8 NPT)

Bulletin 71.1:912N be protected from corrosive chemicals, debris, weather, condensation, or anything else that might clog or enter the spring case. 3.2 (81) 0.2 (5) Regulator dimensions are shown in Figure 3. Capacity Information 2.8 (71) Natural gas regulating capacities at selected inlet pressures and outlet pressure settings are given in Tables 2 and 3. Flows are in SCFH (60°F and 14.7 psia) of 0.6 specific gravity natural gas. To determine the equivalent capacities for other gases, multiply the table capacity by the following appropriate conversion factor: 0.775 for air, 0.789 for nitrogen,...