"Fine Tuning" Hunter Valves with Flow Control Is Easy and Efficient–and Can Reduce Callbacks

No irrigation installation is truly complete without performing a quick and simple valve adjustment to "fine-tune" the water flow for each zone, enabling the entire irrigation system to run at peak efficiency. Todd Polderman, Product Manager responsible for Hunter's wide range of residential and commercial valves, discusses this easy, one-time procedure that will ensure reliable valve performance for years to come.

Hunter Headlines: Explain the purpose of a flow control feature.

Polderman: Flow control is a mechanical means to allow adjustment to the stroke of the diaphragm. A completely open flow control will allow the diaphragm to fully open. A completely closed flow control will not allow the diaphragm to open at all. These are the two extreme positions of the flow control, but it is in the middle ranges of adjustment where the flow control can be most beneficial to the contractor.

By turning down the flow control on a valve, the contractor is mechanically restricting flow, which in turn reduces the pressure to the zone. This reduced pressure can be precisely adjusted for each zone, resulting in optimal head performance.

Since the flow control limits the stroke of the diaphragm to the optimal level for each zone, it provides a secondary function of helping the valve to close more quickly. This can be an important feature for installations where pump systems are used.

Hunter Headlines: Under which conditions is flow control adjustment most beneficial?

Polderman: Flow control adjustment is the most beneficial where the flow and pressure to a particular zone exceeds the requirements of that zone. A typical rotor zone is designed to operate at 60-70 PSI. If you have incoming pressure of 100 PSI, your zone will not operate optimally. You may experience fogging or coverage issues. Adjusting the flow control to limit the incoming pressure will not only provide better rotor performance and better coverage, but will help eliminate a source of customer callbacks.

Hunter Headlines: We understand the adjustment process is simple, no matter which valve is being tuned. Can you outline the procedure?

Polderman: Step 1. Turn on the zone, look at the performance of your heads, and evaluate if you need to adjust the flow control because of too much pressure. Symptoms of too much pressure are fogging and misting. If you have these symptoms, go to Step 2.

Step 2. Turn down the flow control until the misting is gone and the desired performance is achieved. On spray zones, make sure you don’t over-adjust the flow control because you may see a reduction in the radius of the spray.

Many contractors like to adjust all the flow controls even if there are no visual symptoms, which helps minimize closing speed. This is more tuning to a sound or resistance than the visual tuning described above. With the zone running, turn down the flow control until you either hear or feel resistance. Then turn up the flow control a 1/4 to 1/2 turn.

Hunter Headlines: How often does the Flow Control device need to be adjusted?

Polderman: Typically a flow control will only need to be adjusted once. Some systems that are subject to pressure changes, such as some reclaimed water systems, will need to be periodically checked to make sure the flow control is properly adjusted. In cases where pressures are constantly changing, you may be better served using a valve pressure regulator.

Hunter Headlines: Does Hunter offer a pressure regulator?

Polderman: Yes, Hunter offers the Accu-Set™ pressure regulator.

Hunter Headlines: How do Accu-Set and flow control differ?

Polderman: Accu-Set automatically adjusts the stroke of the diaphragm based on pressure. It compares the desired pressure set on the dial to the incoming pressure and lowers the diaphragm to match the desired pressure. So regardless of the incoming pressure, Accu-Set will adjust to exactly what is selected on the dial. I guess you can look at it as automatic flow control.

Hunter Headlines: Which Hunter valves have Flow Control?

Polderman: All of Hunter’s commercial valves (ICV, 1 1/2" and 2" PGV, and HBV) and anti-siphon valves (PASV-075, PASV-101) have flow control as standard. Flow control is an optional feature in all Hunter residential 1” valves.

Hunter Headlines: Anything else to add to ensure efficient and smoothly operating valves?

Polderman: A very common oversight I see in the field is not properly sizing valves. My advice to our readers is to size your valves based on your flow needs, not your pipe size.

Let’s look at a brief example. A 2" installation using Class 200 pipe can safely flow 55 GPM. Since we have a 2" main, some contractors and specifiers would install a 2" valve. But if you look at the valve pressure loss charts for the Hunter ICV you’d get better performance from a 1 1/2" ICV. Valves are designed to function best in the center of the performance envelope.

So by downsizing in our example, we gave up less than 1.5 PSI in pressure loss, but we gained a better performing valve, quicker closing, and you saved yourself some money by purchasing a smaller valve. You really can’t go wrong by sizing your valves to your flow needs.