The Pro's and Cons of a Motor Actuated ball valve and a Solenoid Valve

Why use a solenoid valve?

Positives:

+++ Solenoid valves offer fast, reliable on/ off control for most clean gases and fluids under 50 centistokes, with life expectancy exceeding 1 million cycles.

+++Solenoid valves are typically much less expensive than motor actuated valves, however the Connexion ABVM + ABV units now provide a very cost-effective and reliable option.

+++ Solenoid valves are typically normally closed (failsafe closed) by design, the option for a normally open (failsafe open) function can be achieved in some instances by simply changing the armature assembly.

+++Solenoid valves can be repaired by replacing either seals or replacing the solenoid coil with same or different voltage.

Negatives

--- Media must be clean and free from contaminants and debris to avoid failure to seal.

---Solenoid valves typically control flow in one direction (uni-directional) inlet to outlet only, except for coaxial valves

---Solenoid valves require power to stay in position, typically 5 to 20 Watts up to 100+ watts for large zero rated solenoid valves. 

Except Latching solenoid valves that require a short electrical power pulse to stay open, <> a reverse polarity electrical power pulse will stay closed. (Swap +ve/-ve to -ve/+ve)

---Solenoid valves are typically fast acting 10-100 mSec, which will cause water hammer with fast moving water.

However, the PU220D series WRAS approved solenoid valve is designed to close more slowly 250-500mSec to reduce water hammer. A water hammer arrestor can be installed.

---Choosing the right solenoid valve according to pressure, flow and media can be confusing. Different solenoid valves require either a minimum pressure difference between inlet and outlet and are affected by back pressures from downstream systems, valves or spray nozzles.

2/2 way normally closed assisted lift diaphragm (Typically 0 to 10 Bar)	2/2 way normally closed pressure assisted diaphragm (Typically 0.5 to 10 Bar)
2/2 way normally closed direct acting (Typically 0 to 10 Bar)	3/2 way normally closed direct acting (Typically 0 to 10 Bar)

---Solenoid valve coils get hot when energised and can exceed +100°C after 20 minutes.

---Solenoid valves used for hard water can suffer from limescale build up if the coil stays hot for long periods of time.

---Solenoid valves are an electro mechanical device that generates a magnetic field to move an internal plunger, this can attract any metal and rust particles typically found in most non-filtered mains water systems.

---The flow path through a solenoid valve requires several changes in direction that will reduce flow.

---Position feed back for a solenoid valve is an expensive additional cost.

---Manual override facility for a solenoid valve can be an expensive option. Unless you use a solenoid commissioning magnet.

Why use a motor actuated ball valve?

Positives.

+++Motor actuated valves offer reliable on/off control for most fluids and gases, even contaminated and think glutinous media up to 500 centistokes.

+++Electric actuators only require power to move and do not produce heat to stay in position, so are ideal for hard water areas to avoid limescale.

Power open / power close will stay put when power is removed.

Failsafe return back to the start position when electrical power is removed.

+++The Connexion ABVM motor ball valve only requires 5 Watts to move and under 1 Watt to maintain powered position.

+++Electric actuators do not produce sufficient magnetic field to attract rust or metal debris from mains water systems.

+++Motor actuated valves are unlikely to produce water hammer caused by fast moving liquid media when either opening or closing due to the 5 to 20 second open or close time.

+++Full flow ball valves typically offer full unimpeded bidirectional flow in either direction with minimal drop in pressure and flow.

+++Motor actuators are typically supplied with manual override and position feed back switches or as an option with minimal extra cost.

 

Negatives.

---Motor actuated ball valves are slower to react and can require 5 to 20 seconds to fully open or close.

---Motor actuated ball valves are typically more expensive, bigger and heavier than solenoid valves up to about 2 inch port. However, the Connexion ABVM and ABV actuator units are very cost-effective and extremely compact.

--- Motor actuators are typically limited to 1 cycle every 2 to 5 minutes, with a cycle life expectancy up to 20,000+ cycles.

The Connexion ABVM and ABV units can cycle every 30 seconds, with a cycle life exceeding 70,000 cycles.

---Electric actuators typically cannot be repaired and need to be replaced, unless with ISO9211 mount where the head unit can be replaced without removing or isolating the valve body.

Conclusion:

If you need fast on off control for regular short periods of time for clean fluid or gas media, have a guaranteed pressure difference between inlet and outlet, use a solenoid valve.

If the valve is to be powered on for long periods of time to control dirty or contaminated media; hard unfiltered water; with or without a pressure difference or could have flow in either direction, use a motor actuated ball valve.