Welcome to the Irrigation Valve Buying Guide!
The purpose of this guide is to explain what valves are used for, why they are important, how they work, who needs them, and finally, how to choose a valve.
What are valves used for?
Irrigation Valves are used to create various watering zones in an irrigation system. This separation allows for different watering devices to be encompassed in a single system. By the opening and closing of a valve, each zone in your irrigation system can be watered according to the needs of that zone (such as pressure requirements or limitations, watering frequency or duration).
(Pictured: RainBird DV/DVF Series Valves)
Why are valves important?
Valves allow for one system to be split into various zones. Why is this necessary? Not all zones in an irrigation system should be watered the same. Some zones may require devices with higher pressure, while other zones may require very low pressure.
Additionally, a water source can only provide so much water at once. Often times in larger systems, the water source cannot supply the volume of water needed to water the entire system at once. By creating zones, this ensures the water source is not over taxed, and that each watering device is receiving the flow rate required for optimal performance. (To check the flow rate of your water source, here is our flow rate calculator).
Different zones can also be programmed to have longer durations or more frequent watering times, depending on the needs of each zone. Below are examples of areas that should be in separate watering zones for various reasons:
Lawns and shrubs
Sunny and Shady areas
Spray heads and Rotors
Drip Irrigation and sprinklers
(Pictured: RainBird Nozzle)
How valves work:
When idle, water flows into the inlet and fills the bonnet chamber above the diaphragm. The pressure from the water holds the diaphragm in place, keeping the valve shut.
First, an electrical signal is sent from the controller to the valve solenoid. The solenoid coil becomes an electromagnet, and pulls the plunger up into the solenoid, which allows the water in the bonnet chamber to flow through the outlet of the valve, decreasing the pressure above the diaphragm.
Now that the pressure above the diaphragm is decreased due to the water flowing out, the water from the inlet can then rise high enough to push the diaphragm up, which opens the valve, allowing continuous water flow through it.
Once the flow of electricity to the solenoid stops, the plunger drops inside the solenoid and the water stops flowing in the solenoid dump port.
After the bonnet chamber water pressure above the diaphragm becomes high enough to offset the water pressure below the diaphragm, the valve closes.
(Pictured: RainBird DV/DVF Series Valve)
Who needs a valve?
Valves are typically used with systems that incorporate a manifold and a controller. Controllers and manifolds are not normally used in applications with hose bibbs as the water source. If you will be zoning your system using a controller and manifold, you will need valves in order to operate each zone.
It is also important to note that devices, such as backflow preventers, filters, and pressure regulators are not designed for constant pressure, and are recommended to be installed after the valves, to relieve the constant pressure.
How to choose a valve:
In order to choose a valve best suited for your system, you will need to understand the various types of valves and their different features. Here are the factors to consider when choosing a valve; the power source, type of valve, the features offered, materials it is made from, size of the valve, and the limitations and capacities of the valve.
Then, with this information, you will want to gather the system requirements of your system and each zone (flow rate required for each zone, as well as the PSI) in order to choose a valve that will be compatible with all watering devices and their specific needs.
Power Source:
There are two operation types when choosing valves, manual and automatic. Automatic valves come in two options; Alternating Current (AC) and Direct Current (DC).
Today, the most commonly used sprinkler control valves are electric powered, using 24 volt alternating current (VAC) solenoid valves. These electric solenoid valves are turned on and off by an irrigation controller, which eliminates the need for you to constantly open and close a valve manually. Each zone can be programmed individually, allowing for total customization of your irrigation system. Anti-siphon and globe (angle and inline) valve styles are all available as automatic valves.
Most 24 VAC valves and controllers are compatible with each other, however, that being said, if you will be using different manufacturers for your controller and valves, it is always best to double check compatibility with the manufacturer.
The most common exception to this rule are valves operated by controllers that are battery or solar powered (DC). A DC solenoid valve will not work with an AC powered controller, even if they are the same brand or manufacturer.
Caution: Do not confuse battery powered controllers (DC controllers) whose only source of power is their battery, with the AC controllers that have an internal battery to back up their programing in case of a power failure.
DC valves and controllers are a great option when you want to automate a zone and AC power is unavailable in the location. Only DC solenoid valves will be compatible with DC controllers. In some cases, an AC solenoid may be replaced with a compatible DC solenoid to convert a the valve to DC.
Takeaways:
Prior to purchase and installation, we recommend confirming your controller and valve specifications are compatible.
AC controllers and AC valves are compatible, DC controllers and DC valves are compatible. On many valves a DC solenoid may be used to replace an AC solenoid in order to convert a valve from AC to DC.
Types of valves:
There are three basic styles of control valves to choose from. The angle valve, anti-siphon valve and the globe valve.
Angle Valves:
Angle valves are typically buried, and are similar to globe valves in their recommended applications. However, the angle valve is constructed a bit differently. This type of valve features an additional inlet at the base of the valve. This feature creates a 90-degree angle between the inlet and outlet connections. This allows for moderation of pressure, incase a pressure drop occurs within the valve. If pressure fluctuations are prevalent in your system, angle valves are going to be a better choice than standard globe valves.
Anti-siphon Valves:
Anti-siphon valves are designed with a backflow prevention device built into the valve and are available in 3/4” and 1” size. This is important if you are going to use fertilizer or other contaminants in your irrigation system. Backflow prevention is a must, as you do not want any contaminants flowing backward into your drinking water source. Another difference from globe valves is that anti-siphon valves must be installed above ground and at least 6” higher than the highest sprinkler head. The elevation is needed to make sure the backflow prevention feature works correctly.
Globe Valves:
Globe valves are common in commercial landscape systems and are typically buried under ground inside a valve box. Globe valves come in many sizes; however, they are not available with internal backflow preventers. So while globe valves are less expensive than comparable anti-siphon valves you should consider the cost of having to buy a separate backflow preventer when designing your irrigation system, as backflow prevention devices can be expensive, but they are necessary to protect your water source.
Additionally, some municipalities require specific backflow certified devices. It is always a good idea to double check the requirements of your area when setting up an irrigation system.
Specialty Valves (Globe Style):
These are also a form of globe valves, however these speciality valves offer additional features not normally included in valves. This includes push-to-fit valves that make installation easy, and all-in-one valves which feature a pressure regulator and filter as part of the assembly.
Takeaways:
Choosing between an angle, anti-siphon and globe valves comes down to a few choices.
Do you want to bury the valve? If yes, then you would use either an angle or globe valve (you will need a separate backflow prevention device).
Do you have noticeable pressure fluctuations? If yes, then an angle valve may be the best choice.
Do you want backflow prevention at each valve, or will this be installed 6” or more above ground? If yes, then an anti-siphon valve is the clear choice.
It is always a good choice to double check the backflow requirements of your area to ensure you are complying with all municipal requirements.
Features:
All-In-One (Filter + Regulator Combo):
One option to consider are the all-in-one valves that feature a built in filter and pressure regulator. These features are only available in globe valves, and can come in very handy if you want to avoid buying extra filters or pressure regulators for specific zone needs.
An example of this is if you were running sprinklers on the majority of the zones, but needed to filter to a finer mesh and/or reduce and regulate the pressure for a drip zone. Many of the all-in-one valves we carry filter to 200 mesh and regulate the pressure at the valve to 30 PSI or below, making them ideal for most drip systems.
As a note, we always recommend verifying the operating pressures and filtration requirements needed for specific watering devices, as these requirements vary across different devices.
Filter Sentry:
Filter Sentry washes the filter clean with a wiper that slides up and covers the entire screen when the valve opens. Even more, the wiper continues to scrub the filter's upper part during valve operation. Filter Sentries can be added after the valve is installed as well. This feature is ideal for dirty water applications that deal with higher levels of debris.
Flow Control:
Flow control handles are an option on angle, anti-siphon and globe valves. These handles regulate the flow of water through the valve when the valve opens (not to be confused with a manual on/off switch). Typically it is a stem connected to the top of the diaphragm that goes up through the top of the valve to the flow control handle. The flow control handle works by regulating how far the diaphragm opens and allows water to go through when the valve opens.
By reducing the flow of water through the valve, this also reduces the water pressure of that valve’s zone. This may make the difference in your ability to get a valve operating correctly in your irrigation system vs. having to replace the valve.
Flow control can also be used to override the automatic open and close function of the valve if there is an emergency, such as the valve being stuck open. Should that occur, the valve can be manually closed, allowing you time to asses the problem.
To manually operate a valve, turn the solenoid a quarter (¼) turn, counterclockwise. You’ll hear the water start to flow, when you are ready to close the valve, turn it a quarter turn clockwise. You do not need to overtighten the solenoid, you’ll feel it stop. Once the valve is closed you will hear the water stop.
Considering the minimal additional expense to purchase a valve with flow control is money well spent on your irrigation system in the event of a valve that is stuck open or a valve that is causing trouble due to too much water pressure.
Jar-Top:
Jar top valves are globe valves that have eliminated the need for tools when disassembling the valve. These valves feature a threaded bonnet, instead of one that requires screws to hold it in place. Just as you would open a jar by turning it to the left, the same is true for these valves. Hence the name, “Jar-Top”, making it incredibly easy to get into the valve as needed. Closing it up is just as simple, just turn to the right until the threads stop.
Manual Bleed (Internal and External):
Manual bleed features are options on angle, anti-siphon and globe valves. The item description of the valve will indicate if an internal or external (or both) are featured. 
The external bleeder screw can be used to manually flush the system of dirt and debris during installation and system start-up. This can be located typically in the center of the flow control handle or on the top of the valve. By opening the manual bleeder screw, it allows the water and debris to evacuate out through that hole.
Internal bleed is used for spray-free manual operation. This operates the valve without allowing water into the valve box; on valves with pressure regulation, this allows the pressure regulator to be adjusted without turning on the valve at the controller first. The internal bleed feature is part of the solenoid. In order to do this, you will have to manually operate the valve using the solenoid.
Push-to-fit:
This feature is offered on the globe valves we carry, and makes setting up your irrigation system significantly easier. Push to fit fittings include: PVC-Lock and Blu-Lock. It is incredibly important to note that PVC-Lock and Blu-lock fittings are proprietary in design.
PVC-lock fittings are only compatible with PVC pipe. Blu-lock fittings are only compatible with Blu-lock Tubing. For your convenience, here is a link to our Blu-lock tubing. For more information on these push-to-fit fittings check out our Blu-Lock and PVC-Lock article.
Reverse Flow:
This feature is available on the globe valves we carry, and it essentially works as a preventative and proactive maintenance device. The preventative part of this feature is typically, (and this is not always true) when a reverse flow valve fails it won’t let the valve turn on. This means there is less risk of flooding and damage from broken valve. When a forward flow (normal flow) valve fails it won’t turn off, which can cause flooding and possible damage.
The proactive part of this device is that with reverse flow valves, usually the diaphragms last a little bit longer than regular valves. This is because the internal construction is different and is designed to relieve pressure and undue stress on the diaphragm, thus giving it a longer life.
One disadvantage to consider with this design is that when you close a reverse flow valve it takes a few seconds longer to shut off.
Slow Close:
A feature to consider if you’re worried about water hammer is a slow closing design. This feature is made to reduce water hammer; resulting in less stress on the system. This is offered in both angle and globe valves.
Here is a list of some of the valves we carry with a slow close feature:
Hydro-Rain HRB Series Commercial Valves
Irritrol 700 Series Valves, Irritrol 200B Series Valves,
RainBird PGA Valves, RainBird Inline Plastic Industrial Irrigation Valves
Takeaways:
If you will be using your valve in a drip system, an all-in-one valve may be a good choice, as it offers features such as filtration and pressure regulation, meaning you do not have to buy an additional filter or pressure regulator for your system.
A filter sentry is a good feature to consider if you have dirty water in your system.
Flow control is a feature that allows for manual operation of the valve, enabling you to decrease flow and thus, pressure, as needed. It is also a helpful feature in troubleshooting a valve.
If you want a valve that is easy to disassemble to service, Jar-top valves are a great choice, as they require no tools.
Manual bleed features are a great idea if a valve will need to be flushed, or if manual operation will need to happen in order to adjust or program the valve without turning on the controller.
Push to fit connections make set-up incredibly easy, but it is also paramount that these connections are used with the compatible tubing or pipe.
Reverse flow valves are a great measure to preserve and protect the longevity of your valves and ultimately your system. One drawback to remember is that they do take a little bit longer to close.
Slow close is a great feature if you are worried about water hammer or stress in your system.
Choosing a material:
Brass vs. Plastic Valves
When a valve is buried underground the reliability of both plastic and brass valves are nearly the same. With the reliability being so similar when buried, price is what drives the majority of sprinkler installers to use plastic valves.
If your valves will be above ground, then you may want to consider a brass valve as the plastic degrades over time when exposed to UV radiation. A fix for this would be to build an enclosure around the plastic valves shielding them from UV rays.
We carry a very large selection of plastic valves. We currently do not carry Brass Valves.
How to pick the right Size of valve?
This is probably the most challenging aspect of choosing a valve. Most people think that if you have 1” PVC pipe in your irrigation system then you need a 1” valve. This is not always the case, and this thinking could get you in trouble down the road.
Automatic valves get a jump start on opening by receiving an electric charge sent from the controller to the solenoid. However, the heavy lifting is done by the water pressure. There has to be enough pressure loss at the valve to allow it to open and close by itself. With that in mind, too much pressure loss will cause the valve to “snap” closed too quickly which will cause the value to wear out quickly; this “snap” when closing can also cause water hammer to occur.
A good rule of thumb to follow is the maximum static pressure loss from the mainline should not exceed of 10% of the static pressure available in the mainline.
Additionally, the valve should either be the same size as the largest pipe or no more than one nominal size smaller.
The size of the automatic valves is determined by the manufacturer’s recommended flow range, together with the pressure loss through the valve at the selected flow. You will need to get the valve manufacturer’s flowchart for the model of valve you plan to use. This information should be on the valve packaging. If you can’t find it on the package, try the valve manufacturer’s website. How do you choose the right size of valve then? You will need to look at the manufacturer's flow chart. You want to to keep the pressure loss below 6 PSI (to avoid “snap” closing).
Please visit the valve item page for each specific pressure loss chart.
Valve Capacities and Limitations:
Lastly, the final factor to consider when choosing a valve is the specific operating conditions and restrictions of the valve. A good rule of thumb when choosing any system components is to check the flow rate capacities and the pressure (PSI) requirements and limitations. All valves require a minimum flow rate and a minimum PSI in order to operate properly.
In addition to the minimum requirements, all valves have limitations and capacities. All valves will list a maximum flow rate and PSI. It is incredibly important to stay within the operating ranges listed; as exceeding any of these limitations can result in damage or failure of the valve, which could lead to possible system damage and flooding.
Please see our chart below for specific manufacturer and model information:
Valve Links:
If you have any further questions about valves, please feel free to reach out to our helpdesk for all your irrigation valve needs!