Frequently Asked Questions - Valves
We have instituted a gate valve exercising program for our community. What valve turning equipment does USABlueBook have to offer?
USABlueBook offers everything from simple gate wrenches to powered valve operators. Electric, air, hydraulic and gasoline-powered operators are listed in our current catalog. A wide assortment of valve box wrenches are also offered.
Do you have a solenoid valve for dirty water with some debris?
| No, but…! Solenoid valves are designed for liquid without debris. Internally, they operate with close tolerances and often have small internal ports for pilot operated actuation. Likewise, motorized ball and butterfly valves are not recommended for this kind of service. The answer is to use a diaphragm valve, which is recommended for aggressive liquids and light slurries. |
| Electric powered diaphragm valves are available, but are very expensive and have very slow open/close times. The most economical solution for making a diaphragm valve operate like a solenoid valve is to utilize a pneumatic actuator. Don’t have a source of air? For less than $250 you can buy a high quality tank mounted air compressor that can serve as a central air system for powering any number of pneumatic valves. The total cost of a diaphragm valve with pneumatic actuator, control valve and compressor, is surprisingly low relative to the alternatives that are available. |
What can I do to prevent water hammer in my system?
| Water hammer can be very destructive to both pumps and pipe. If water hammer occurs when pumps shut down, it may be due to a check valve slamming shut as the water in the line reverses direction. If this is the case, there are a variety of slow closing check valves that can solve this problem. |
| Another cause could be air entering the suction side of a pump leading to cavitation, which can literally pull metal out of impellers and cause tremendous line surges. Air trapped in water distribution lines can also cause water hammer. Air/vacuum valves for well pumps and air release valves for pressurized lines can help solve these problems. |
What do we do about customers who don’t pay their sewer bills?
| Yes. USABlueBook has a valve that is specifically designed for this purpose. It is called the Sewer Valve and it’s installed with a riser pipe to serve as a cleanout for a 4" SDR36 PVC sewer line. The inside of the housing is also designed to accept a special coarse threaded plug that can be inserted through the riser and tightened to restrict flow by 90%. Water from a leaking faucet will flow through, but solid matter will stop up the line very quickly. If you think cutting off the water makes bill collection easier, wait until you close off the sewer line! |
| For more details, look for stock number 34085 and 34086 in the Valve section of your USABlueBook catalog. |
My solenoid valve isn’t closing when the coil is de-energized. What can cause this?
| Usually we see the problem related to one of two situations. The first situation involves dirt. Solenoid valves have small internal ports leading to the actuation mechanism that can be clogged by foreign particles in the liquid. Remember, solenoid valves are not designed to handle liquids with solids. USABlueBook can supply other types of actuated valves that are suitable for “dirty” liquids and slurries. |
| The second situation involves improper differential pressure. Some solenoid valves’ actuators require a minimum differential pressure between the inlet and outlet ports. For example, if you are using a solenoid valve to fill an open tank from a pressurized water line, you obviously have plenty of differential pressure between the inlet and outlet side. However, if you were using a pump to supply water to a pressurized line (eg. a gas chlorine injector feed line), when the pump shuts off the backpressure at the discharge side of the valve may equal or actually exceed the supply pressure on the inlet side. In this example the valve will not close. |
| In this type of application select a solenoid valve designed for operation with “0” pressure differential. Even these will not work correctly if the line pressure on the discharge side of the valve exceeds that on the inlet side. For these applications you will need to install a check valve after the solenoid valve so that pressure on both sides of the valve will equalize. |
What is the difference between a double check valve backflow preventer and a reduced pressure zone backflow preventer (RPZ)? Where is one used versus the other?
| Double check valve backflow preventers contain two independent check valves in one housing. Test cocks are located at strategic points so that the check valves can be tested with a backflow preventer test kit. Double check valves are used for non-health hazard cross connections in continuous pressure applications. |
| RPZ backflow preventers include two check valves like a double check backflow preventer, but they also have an intermediate relief valve that opens to atmosphere if both check valves should fail. Because of this extra measure of protection RPZ backflow preventers are used in cross connections subject to backpressure or back siphonage where there is a potential health hazard in continuous pressure applications. |
What is the difference between wafer style and lug style butterfly valves?
| Wafer style is the more common and less expensive of the two types. The wafer style butterfly valve is installed between two flanges. The valve is held in place because it is surrounded by the bolts attaching the two flanges. This of course makes dead end service or disassembly of one side of the piping system impossible. |
| This is where the lug style is necessary. A lug style has threaded inserts on both sides of the valve body and is installed using two sets of bolts and no nuts. This allows either side of the piping system to be removed while the valve remains in place. Pressure ratings, however, are reduced when used in dead end service. |
Viton or EPDM. What kind of seals do I need?
Almost all valves are offered with a choice of Viton or EPDM seals. The most common applications in the water and wastewater industries are chlorine (sodium hypochlorite) and caustic (sodium hydroxide). Viton is necessary for use with chlorine, and EPDM is necessary for use with caustic. There are many other chemicals out there, and some cases, other seal materials available. Please contact our tech support department for advice.
I see most of your actuated valves are offered with standard control or 2-wire control. What is the difference?
| The simple answer is that 2-wire control is desirable when replacing a solenoid valve with an actuated valve. The 2-wire control allows you to use the same switching mechanism as was being used for the solenoid valve. The true difference is this: |
| 2-Wire Control: Power is applied to motor at all times through two leads leading to actuator. SPST control switch is connected to two separate leads. Valve will remain open or closed depending on whether the SPST control switch is open or closed. If power is removed, the valve will remain in its present position. |
| Standard Control: Power is applied to the actuator at all times through at least one of two leads leading from the SPDT switch. The valve will open or close to a fixed position depending on which of the two lead wires is energized. If power is removed, the valve will remain in its present position. |
I need an actuated valve that will close automatically if there is some kind of power failure. What are my options?
Most valve actuators are electric or pneumatic. Some electric actuators are available with a spring return, which will cause the valve to close whenever de-energized. However, most electric actuators do not work this way. For an electric actuator to close in the event of power loss, a battery back-up is required. In most cases, this option costs more than the valve and actuator combined. If compressed air is available, a pneumatic actuator is always the economical option. Most pneumatic actuators are designed to open with air pressure and spring close.
My reduced pressure zone (RPZ) backflow preventer is discharging water from the relief valve. Is there an easy way to diagnose the problem?
Yes. Follow these steps. First, close #2 shut-off valve. If the discharge stops, the problem is a fouled second check. If discharge continues, open #4 testcock. If the discharge stops or is reduced, the problem is a fouled first check. If the discharge continues, the problem is most likely in the relief valve. Disassemble and clean the affected components and remove any debris from the backflow preventer. If any parts look damaged, they made need to be replaced.