Steam Solenoid Valves
Steam rated valves and high temperature solenoid valves are generally either Brass, Bronze or Stainless Steel body with PTFE seals suitable for temperatures up to +200C or a maximum steam pressure or 12 Bar. Generally the temperature of steam is directly related to the pressure and most solenoid valves on the market today are rated to 10 Bar steam at +185C, with higher quality valves being rated to 12 Bar or +200C.
High temperature solenoid valves are controlled by a solenoid coil which is basically an electric magnet or copper wire wound around a bobine (a bit like a cotton reel) so when electricity is passed along the wire it generates a magnetic field. This in turn can lift or move an internal armature (typically magnetic stainless steel 430F) within the valve to either expose a pilot hole, lift a plunger or piston assembly so the media being controlled can pass through the main valve body.
Steam Valve Function.
Steam solenoid actuated valves are typically 2/2 way, being 2 ports, inlet and outlet and 2 positions, either OPEN or CLOSED. This function can be either normally closed (most commonly used) or normally open.
2/2 way normally closed - meaning fail-safe closed requires electrical power to open.
2/2 way normally open - meaning fail-safe open requires electrical power to close.
Steam Valve Operation.
The operation of a steam or hot media solenoid valve can be one of two ways:
Direct Acting - the valve operates directly from the coil, these operate from zero pressure up to the maximum design pressure, typically 0 to 10 Bar.
Sometimes referred to as assisted lift, kick pilot or zero-rated valves.
Pilot Assisted - the valve operates indirectly from the coil via an internal pilot, these operate with a pressure differential i.e. a minimum pressure difference between inlet and outlet pressure typically either 0.5 Bar 7 psi or 1 bar 14.7 psi.
Sometimes referred to as pilot operated, servo assisted and floating piston valves.
Helpful Hint: Coils need to dissipate heat so allowing cooler air to circulate and not covering them
Class F coils are rated to 155C, basically the copper wire can withstand a working temperature up to but not exceeding 155 C. This is the most common form of solenoid coil and are ideally suited to working ambient temperatures up to +20C and media up to +100C. (Typically Not suitable for steam applications)
Class H coils are rated to 180C, basically the copper wire can withstand a working temperature up to but not exceeding 180C. These are the most common form of solenoid coil and are ideally suited to working ambient temperatures up to +50C and media up to +180C. (Suitable for most steam applications)
Class N coils are rated to 200C, basically the copper wire can withstand a working temperature up to but not exceeding 200C. This is the most common form of solenoid coil and are ideally suited to working ambient temperatures up to +80C and media up to +200C. (Suitable for most steam applications).
With all the demands of pressurised steam; hot water, hot air and hot oil applications we have compiled a range of high quality 2/2 way steam solenoid valves with Class N Rated coils and 100% duty rating.
Duty Rating.
Duty rating (duty cycle being the power on time and power off cool downtime). The duty cycle of a solenoid coil is expressed as a percentage of the coil power off time (cooling time) divided by the time powered ON + time power off (cooling) x 100 to give a percentage.
Duty Cycle = Time OFF / (Time ON + Time Off) x 100
Example: Coil powered ON for 15 seconds and then switched / powered OFF (cooling time) for 45 seconds before powered ON again then the cycle time is calculated as:- Duty cycle = 45 seconds / (15 ON + 45 OFF) x100 Duty Cycle = 45 / 60 x 100 Duty Cycle = 75%
Example: Power ON 2 minutes, then power off 2 Minutes. Duty Cycle = 2 / (2+2) x 100 Duty Cycle = 50%