TILI Automation

 Because there are so many potential reasons for solenoid valves to malfunction, they are often thought to be complex, trouble-prone devices. Actually, they are quite simple and very reliable. Many of the problems originate outside the valves themselves, while others are caused by mis-application or improper installation. Troubleshooting should begin with a check of the voltage and pressure input. The problem may be caused by an inoperative control relay or a fluctuating pressure regulator. If voltage and pressure are correct inspect the valve. The main reasons a direct-acting solenoid valve fails to operate: ● Low or no voltage ● Burned-out solenoid ● Pressure higher than the valve’s rating ● Foreign matter in the valve ● Binding core or damaged core tube To operate properly, a solenoid valve core must move within the core tube and contact the plugnut when the coil is energized. You should hear a sharp metallic click at energization. Absence of the click usually indicates an elect...

 A solenoid valve is a combination of two functional units: A solenoid operator essentially consisting of a coil, core, core tube, shading coil and spring(s). A valve body containing orifices in which a disc, diaphragm or piston etc. is positioned according to the type of technology used. The valve is opened or closed by movement of the magnetic core which is drawn into a solenoid when the coil is energized. SOLENOID VALVE TERMINOLOGY Coil Electrical part of the valve consisting of a spool wound with insulated copper wire creating a magnetic flux when energised. The coil is held in place on the tube with a retaining clip. Core Soft-magnetic plug-nut moved by magnetic forces (flux generated by the coil). Core spring Spring which keeps the core in fixed position when the coil is de-energised. Core tube Stainless steel tube closed at one end, in- stalled to improve the magnetic flux of the solenoid coil upon energisation Cover Cover mounted on the valve body and incorporating a number...

 Solenoid Valve Working Animation 1. The above shown animation is an example of normally closed  solenoid operated valve . 2. When there is no supply voltage to SOV then it will be in Normally Closed condition (default). 3. When the  Switch  was closed then power will be passed through the Solenoid coil, then energizes the coil. The energized solenoid coil acts as magnet and lifts the core or plunger ( Center Part of Solenoid) of the solenoid. 4. As the core or plunger of solenoid moves towards upsides, this movement creates a open flow.

 This instrument is not new to me. Since We started our pneumatics class on my third year in college, I already had the pleasure to meet this instrument. We even had to use this almost everyday, during our laboratory exercises. Its always present in all our pneumatic and hydraulic trainers. How does this stuff really work? 5 Port 2 Position Valve A  valve  is a device that regulates the flow of fluid (gases, liquids,fluidized solids, or slurries) by opening and closing or partially obstructing passage ways. A 5/2 way  directional valve  from the name itself has 5 ports equally spaced and 2 flow positions. It can be use to isolate and simultaneously bypass a passage way for the fluid which for example should retract or extend a double acting cylinder. There are variety of ways to have this valve actuated. A solenoid valve is commonly used, a lever can be manually twist or pinch to actuate the  valve , an internal or external hydraulic or pneumatic pilot to m...

 Manual Reset Solenoid Valves are used in applications and processes demanding utmost safety checks before starting / stopping the process. In all such application, human intervention is the final check before the process is taken into/ taken off the auto mode. Based on the nature of the process, the solenoid valves are required to stop the process from starting automatically in case of an emergency or vice versa. These valves are called Manual Reset valves with Latching on Energization. They are also referred to as No voltage Release or Free handle type Manual reset. Manual Reset Solenoid valves Types & Operation 1. Manual Reset, (Latching on energization) This valve is to be used for application which demands utmost safety check before starting of the process. Valve cannot be operated electrically. The valve switches ON when electrical supply to the solenoid is available followed by manual operation. In absence of power to the solenoid, the valve can be operated manually. Val...

 A solenoid valve is an electromechanical controlled valve. The valve features a solenoid, which is an electric coil with a movable ferromagnetic core in its center. This core is called the plunger. In rest position, the plunger closes off a small orifice. An electric current through the coil creates a magnetic field. The magnetic field exerts a force on the plunger. As a result, the plunger is pulled toward the center of the coil so that the orifice opens. This is the basic principle that is used to open and close solenoid valves. “A SOLENOID VALVE IS AN ELECTROMECHANICAL ACTUATED VALVE TO CONTROL THE FLOW OF LIQUIDS AND GASES.” Circuit Functions of Solenoid Valves Solenoid valves are used to close, dose, distribute or mix the flow of gas or liquid in a pipe. The specific purpose of a solenoid valve is expressed by its circuit function. A 2/2 way valve has two ports (inlet and outlet) and two positions (open or closed). A 2/2 way valve can be ‘normally closed’ (closed in de-energi...

 Flow Coefficient Kv DEFINITION KV-VALUE: AMOUNT OF FLOW (M3/HOUR) OF WATER OF 20°C IN A VALVE WITH A PRESSURE LOSS OF 1 BAR. The amount of flow of a fluid through a (solenoid) valve can easily be calculated with flow coefficient Kv. Please note that for gases (e.g. air) a different formula is used (see correction factor gases below). The Kv-value expresses the flow rate of water in m3/hour in a valve with a pressure loss of 1 bar and a temperature of 20°C. Pay attention that the Kv-value is expressed in m3/hour, while the kv-value (lowercase!) is expressed in l/min. To calculate the flow rate the following formula is used: where: Q = flow rate of liquid (m3/hour) Kv = flow coefficient (m3/hour) SG = Specific Gravity (=1 for water) dp = pressure differential over the valve (bar) The Kv-value of a valve is determined by a standardized test according to VDI/VDE 2173. For this purpose a test set-up is used, such as shown in the following schematic drawing: Cv & Kv Relation : Somet...

 A solenoid valve is an electro-mechanical device in which the solenoid uses an electric current to generate a magnetic field and thereby operate a mechanism which regulates the opening of fluid flow in a valve. Two Solenoid Valves Two Solenoid Valves are used in order to have redundant air supply arrangement to valve. Now consider following cases: Both SOV A & B are Energized: In this case air supply is through SOV A, since SOV B exhaust is blocked because vent port of SOV A is closed. SOV A Failed and SOV B Energized: Since SOV A is failed so vent/exhaust port of SOV A is now open, hence exhaust of SOV B will go via vent port of SOV A to SOV exhaust port. SOV A Energized and SOV B Failed: Now SOV B vent port/exhaust port is open and SOV A is in line, but at the time of SOV A  de-energizing vent of SOV A will pass via exhaust port of SOV B to vent port of SOV A. Hence depresurizing the system.

 Directional control valves perform only three functions: *stop fluid flow *allow fluid flow, and *change direction of fluid flow. These three functions usually operate in combination. Classification of Directional Control Valves Directional control valves can be classified according to- *number of ports *number of positions *actuating methods *type of spool. Example: A 5/2 directional control valve would have five ports and two spool positions. Number of Ports Ports that will be counted shall be external ports only. 5/2 Number of Positions Including the normal and working positions which a valve spool can take there are types like two position, three position and proportional valve … Actuating Methods Manual, spring, electrical, pneumatic, and hydraulic. Manually Operated Manually operated valves work with simple levers or paddles where the operator applies force to operate the valve. Spring force is sometimes used to recover the position of valve. Some manual valves utilize eithe...

 The valve is 3/2 Direct Acting pressure balance design i.e. area at the Seat (Part-19) and balancing Plunger O Ring (Part- 80) are same, thereby air force acting on the Plunger Seat is nullified which makes the valve to work merely on the spring force throughout its pressure range. 3 Port 2 Position Direct Acting Solenoid Valve In the de-energised condition of the valve Port-1 is blocked and Port-3 is connection to Port-2. Port-4 is connected to spring chamber of the Actuator which is connected to Port-3 also. On energizing the valve, Plunger (30) pulls up thereby connecting Port-1 and Port-2 and blocking Port-3. Port-4 remains connected to Exhaust Port-3. When the inlet is connected to Port-1, air passes through the small hole provided in the Plunger and acts on upper side of Plunger O Ring (80). When the valve is energized, the Plunger (30) pulls up because of which the lower orifice opens up thereby connecting Port-1 to the outlet Port-3 and the upper orifice at Sleeve (Part-10...

 Direct acting, normally closed Solenoid Valve Main features *The sealing element is directly connected to the core *This type of valves does not need any differential pressure to open. *The maximum pressure difference across the valve is limited by the magnetic force of the used coil and the seat diameter. *This valve is commonly used for low flow volumes. Solenoid valve is closed. *The coil is de-energized and the sealing element is pressed on the seat by the force of the spring and the medium. Solenoid valve opens. *The coil is energized and the magnetic force lifts the core with the sealing element from the seat. Solenoid valve closes. The coil is de-energized and the sealing element is pressed on the seat by the force of the spring and the medium. Safety solenoid valves with manual reset, normally open (NO) Main features *The closing function is electrically activated by one or more gas detectors, safety thermostat, gas alarm systems or another control device. *This valve is u...

 Most indirect-acting solenoid valves operate slower than their direct-acting counterparts. This is because air pressure is routed in and out of the pilot to push the spool. Four Way Solenoid Valve While the solenoid rests idle, the core spring pushes it forward against the pilot base. The purpose of the core is to seal against a very small pressure port facing it, which becomes open when the solenoid is energized. When energized, the coil around the core pulls it away from the pilot base, which allows airflow into the pilot itself. This pushes the pilot against the spool, shifting the valve’s airflow as long as the coil is energized. When resetting, the core spring pushes it against the pilot to seal off airflow and also open the pilot’s exhaust ports, which let the pilot reset to its idle position. Some solenoid pilots have a feature known as the manual override as well. This is a small button on the outside of the pilot (between it and the core) which manually pushes the core aw...

 Basics of Pilot Operated Solenoid Valves A solenoid valve has two main parts: the solenoid and the valve. The solenoid converts electrical energy into mechanical energy which, in turn, opens or closes the valve mechanically. A direct acting valve has only a small flow circuit, shown within section E of this diagram (this section is mentioned below as a pilot valve). In this example, a diaphragm piloted valve multiplies this small pilot flow, by using it to control the flow through a much larger orifice. Solenoid valves may use metal seals or rubber seals, and may also have electrical interfaces to allow for easy control. A spring may be used to hold the valve opened (normally open) or closed (normally closed) while the valve is not activated. A- Input side B- Diaphragm C- Pressure chamber D- Pressure relief passage E- Electro Mechanical Solenoid F- Output side The diagram to the right shows the design of a basic valve, controlling the flow of water in this example. At the top figu...

 2/2 Direct Lift Diaphragm Normally Closed Solenoid Valve To open:  when the valve receives an electrical signal, a magnetic field is formed which attracts the plunger covering the main orifice to lift off, causing system pressure to drop. As system pressure on the top of the diaphragm is reduced, full system pressure on the other side of the diaphragm acts to lift the diaphragm away from the main orifice, which allows media to flow through the valve. Since the bleed orifice is dimensionally smaller than the pilot orifice, the system pressure cannot rebuild on the top of the diaphragm as long as the pilot orifice remains open. When the system pressure is 0 PSI, the valve also can be operated. To close:  when the valve is de-energized, it releases its hold on the plunger. Then the plunger forced by the spring drops and covers the main orifice. The system pressure builds up on the top of the diaphragm through the bleed orifice, forcing the diaphragm down until it covers the...