In-stock parts
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In-stock parts
Order by 2PM MST
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2045 West Buckeye Road
Phoenix AZ 85009
United States
Hoffman Specialty Model 79 water main vent valve, part 401488, releases air from compatible hot-water, cold-water and glycol-water mains. The straight inlet provides both 1/2-inch female NPT and 3/4-inch male NPT connection options.
A built-in check valve helps prevent air from entering when system pressure falls. The removable top supports service access, and the 1/8-inch NPT outlet allows a safety drain connection where discharged moisture needs to be directed away.
| Feature | Benefit |
|---|---|
| Built-in check valve | Helps prevent outside air from returning as system pressure drops. |
| Dual-size inlet | Offers either 1/2-inch female or 3/4-inch male NPT connection. |
| Removable top | Provides access for vent maintenance. |
| Threaded discharge | Accepts a piped drain for managing moisture discharge. |
| Specification | Detail |
|---|---|
| Manufacturer / model | Hoffman Specialty 79 |
| Manufacturer part number | 401488 |
| Inlet | 1/2-inch female NPT /3/4-inch male NPT, straight shank |
| Outlet | 1/8-inch NPT safety drain connection |
| Maximum operating pressure | 75 psig (maximum pressure against which the vent can open) |
| Maximum hydrostatic pressure | 200 psig; not the operating venting-pressure rating |
| Maximum temperature | 250°F |
| Fluid selection | Hot or cold water, or glycol-water applications with specific gravity greater than 0.7 |
Select this vent by the actual system pressure and fluid, not connection size alone. The 200 psig hydrostatic limit does not increase the 75 psig operating limit.
| Check | What to confirm |
|---|---|
| Replacement identity | Match Model 79 and part 401488; do not substitute the different Model 78 on size alone. |
| Connection arrangement | Identify which inlet thread your system uses and whether a drain line is required. |
| Service conditions | Confirm pressure, maximum temperature and fluid specific gravity. |
| Installation and maintenance | Follow the manufacturer instructions and provide access to the removable top. Verify the suitability of the vent location and drainage arrangement. |
Need help selecting the correct water main vent? Contact UnitedBuilt through online chat, email parts@unitedbuilt.com, or call 602-253-7750 with your existing part number, connection size and operating pressure.
| Weight | 1.23 lb |
|---|