Irrigation Product Listings & Reviews
Irritrol 311A Anti-Siphon Valve
Description:
The 311A Anti-siphon valve is Irritrol's top-of-the-line anti-siphon valve. At one time this valve was sold under the Hydro-Rain brand name.
Model Numbers:
- 311A-.75 -- 3/4" anti-siphon valve with flow control
- 311A-1 -- 1" anti-siphon valve with flow control
Features:
- Internal and external bleed (flush mode) for manual operation
- Accepts OmniReg® modular pressure regulator
- Flow control allows precise flow adjustment and manual shut-off
- Upper-body and air-vent cap constructed of glass-filled nylon
- Lower-body constructed of UV-resistant PVC
- Rugged, double-beaded nylon-reinforced Buna-N diaphragm provides leak-proof seal
- Buna-N valve seat seal
- All stainless steel hardware and springs
- Unique three-way stainless steel bonnet screws with threaded brass inserts
- Encapsulated injection-molded solenoid
- Captive hex plunger
- Polypropylene float
- Removable, tamper-resistant flow control handle
- Externally removable self-cleaning metering system for dirty or effluent water applications
- Meets listing requirements of IAPMO-UPC and City of Los Angeles
- Flow range: 1-30 GPM
- Pressure range: 10-150 psi
Manufacturer's Performance Data:
| Model | Size | 1 GPM | 5 GPM | 10 GPM | 15 GPM | 20 GPM | 30 GPM |
| 311A-.75 | 3/4" | 5.5 PSI | 6.0 PSI | 8.0 PSI | 9.0 PSI | 11.0 PSI | Do not exceed 20 GPM with 3/4" size |
| 311A-1 | 1" | 5.5 PSI | 6.0 PSI | 7.5 PSI | 8.5 PSI | 10.0 PSI | 18.5 PSI |
Review:
This is a good quality anti-siphon valve, although it is a bit ugly! While Irritrol considers this valve suitable for commercial systems, it should be noted that commercial systems rarely use anti-siphon valves. The nylon upper body is very high quality, but the benefits of the nylon are almost completely defeated by combining it with a PVC lower body. So it has the same pressure rating as the less expensive PVC models. The 311A is actually a hybrid of two separate items. Essentially it is a manual anti-siphon valve body with an electric actuator conversion kit installed on it. An internal bleed means it doesn't spit water when operated manually. A captive plunger makes it easier to work on. This valve can be repaired without removing it from the piping. The optional OmniReg® device allows the valve to control the downstream pressure at a more or less constant level (see separate listing for the OmniReg®).
The 311A anti-siphon valve has very high friction loss compared to Irritrol's other anti-siphon valves. I really don't see the point of spending more money for this valve unless you need the optional OmniReg® modular pressure regulator. If you have water pressure high enough to need the pressure regulator, you probably want a valve rated higher than the 150 PSI maximum for this valve. The rule of thumb is that the pressure rating of a valve should be at least double the actual static water pressure. Take a look at the installation rules for the Irritrol 2700 series anti-siphon valve: Click here. The same important installation rules apply to the 311A and all other brands of anti-siphon valves.