Brochure

84
Vents
Model 4A Part No. 401413
Air Valve (non-vacuum)
• Float-type thermostatic vent
• For residential or small one-pipe or two-pipe systems
• Single non-adjustable port
•
1
⁄2" NPT female and
3
⁄4" NPT
male straight shank
• Install 6-10" (150-250mm) above horizontal return and
18" (450mm) above the boiler water line
• Maximum operating pressure 2 psig (0.13 bar)*
• Maximum pressure 10 psig (0.7 bar)
Model 75 Part No. 401434
75H Part No. 401437
Air Valve (non-vacuum)
• Float-type thermostatic vent
• For medium and large systems
• Single non-adjustable port
•
1
⁄2" NPT female and
3
⁄4" NPT male
straight shank
• Maximum operating pressure*
– Model 75 3 psig (0.2 bar)
– Model 75H 10 psig (0.7 bar)
• Maximum pressure 15 psig (1.0 bar)
Main Steam Vents
Air Valve
Model 4A
Air Valve
Model 75 & 75H
3
13
/16"
(97mm)
1
1
/2"
(38mm)
2
1
/2"
(64mm)
5
3
/4"
(146mm)
How to Select Steam Vents
Model Radiator Convector Unit Thermostatlic
Number (Angle Type) (Bottom Inlet) Heater Mains Vent (only) Remarks
1A X Adjustable Orifice
70A X Fixed Orifice
40 X Fixed Orifice
1B X Adjustable Orifice
41 X Fixed Orifice
43 X Fixed Orifice
45 X Fixed Orifice
71A X Fixed Orifice
71B X Fixed Orifice
71C X Fixed Orifice
508 X Moisture Type
4A X Small Systems
75 X Low Pressure
75H X High Pressure
76 X Vacuum Systems
3XPaul Systems
74 X Unit Heaters
4XSmall Systems
8C X High Pressure
*Drop away pressure (maximum pressure against which the vent can open).
Hoffman Specialty
®
Regulators