Valve Options –Actuated ball valves vs Solenoid valves
When it comes to understanding which valve is the better when specifying a project, there are many things to consider. Often it’s application and environment that lends itself to the type of valve selection. Primarily, the type of valve to use is the place to start! For the purposes of this exercise, we will focus on just solenoid and actuated ball valves.
One of the most often asked questions is should a normally open (N/O) or normally closed (N/C) valve be used. To explain, a normally closed valve does not require any power for it to remain closed and when required to open, an electrical current needs to be connected. For the valve to remain open the current must stay connected to the valve. Conversely, a normally open valve does not require a current for it to stay open but does need an electrical current to close. The electrical current must remain connected to the valve for it to stay closed. There is an argument that says a N/C valve is preferable when used as part of a water leak detection system. The reason for this is that in the event of a water leak, water could come into contact with the electrical wiring and short out the power, if this happens, a N/C valve will shut. Some consideration should be given to the type of N/C valve used as the solenoid valve will become very hot when used with a water leak detection system.
The way a valve size is specified can often cause some confusion. When referring to the size in imperial they are the same as other plumbing parts. When sizing in metric, the size refers to the inside diameter of the pipe. For example a 20mm valve is designed to fit on a 22mm pipe, which has an inside diameter of 20mm.
Once it’s been decided between using a N/C or N/O valve, the next step is to choose which type of valve should be used.
In the case of water leak detection, the choice is between an actuated ball valve and a solenoid valve.
Actuated Ball Valves:
These valves use a stainless steel ball fitted in a cast steel housing and are opened and closed by an electrical motor mounted on the top. The rotating ball has a precision machined hole through the middle of it, bored to the full size of pipe in which it’s being fitted (full bore). The ball rotates through 90° from an open to close or close to open position. The status of the ball, if open or closed can be seen on the top of the valve using the position indicator window. The actuated ball valve can be supplied with a rating of 110 – 230VAC or 9 – 24VDC. During opening and closing the valve draws 5 Watts (@230VAC) and once it’s fully open or closed this drops to 0.03 Watts. It takes around 3 seconds for the valve to either open or close. They can be installed in any orientation and do not require or have any effect on water pressure to work. They are available in sizes between ½” to 2”
These valves are normally supplied with a cast brass housing onto which a magnetic coil is fitted. The valve is opened or closed by energising the coil, which creates a magnetic field, which moves a plunger up and down. When using a normally open solenoid valve, the coil is energised and the magnetic field forces the plunger down, closing the valve. It is the opposite way round for a normally closed valve. This operation takes only 50 milliseconds and uses 6 Watts for valves up to 1” and 10 Watts for valves larger than this. They can be installed in a horizontal or vertical position and the larger valves need a small amount of water pressure to operate. This type of valve is ideal for processes that require the valves to open and close regularly, which is usually not the case when used with water leak detection. The only exception is when connected through a PIR sensor to open and allow water to flow to a WC area, a requirement of BREEAM. They are available in sizes between ½” to 3”
Advantages and disadvantages:
Actuated ball valves when open are full bore equalling the inside diameter of the pipe. Solenoid valves have a diaphragm that lifts and directs the water up and over a cast internal wall. This sometimes puts a restriction on the flow and can in extreme cases cause water hammer to occur.
Solenoid valves can generate high heat levels when energised for long periods of time. Actuated ball valves only have a moderate current to them when opening or closing. They do not generate any heat when fully open or closed.
Actuated ball valves can be installed in any position, horizontal, vertical or anywhere in between. Solenoid valves can only be installed horizontally or vertically.
Solenoid valves open faster that actuated ball valves, 50 milliseconds against 3 seconds.
Actuated ball valves have a position indicator, solenoid valves do not.
Solenoid valves are available in larger sizes (3”), actuated ball valves are only available up to 2”.
Envirotech Alarms only supply normally closed solenoid valves, we do however supply both normally open and normally closed actuated ball valves.
There is very little price difference between solenoid valves and actuated ball valves. In the main the solenoid valve are marginally more expensive.