Solenoid valve control

Act as a solenoid valve, controlled by a pilot solenoid valve. 

VA, VB 3-way solenoid valves controlling the flush/evacuation cycle of collecting bags. 

The metering b.in has a capacity of 1.6 m3 and has a live bottom discharge. A hydraulic motor drives the drag chain conveyor. A hydraulic power unit equipped with an electrically driven pump, flow regulator valve, pressure relief valve, and solenoid valve control the flow and pressure of hydraulic fluid... 

The second indirect method is by measurement of the weight of ethylene oxide delivered from the feed containers to the sterilizer. This method assumes no leakage, liquefaction, or polymerization of ethylene oxide in the gas tines connecting the gas source to the sterilizer. It is recommended that the two indirect methods be used in conjunction with each other. The weight loss method ensures that the increase in pressure is in fact due to gas from the ethylene oxide feed container and not from diluent gas or some other source whereas the pressure method provides an ongoing index of gas concentration during the exposure period. Gas makeups should be automated and specified to be drawn from the ethylene oxide feed tanks, not from the diluent gas. Gas makeup may be controlled by pressure switches or by pressure transducers connected to solenoid valves controlling gas flow. 

TMACE SUCH CHANNCtS TO MEASURE ACTIViTt M S6 FUEU ELEMENT OISCHAROC STREAMS. SOLENOID VALVES CONTROLLED BY THE. RieOROERS BRING WATER TO THE IONIZATION CHAMBER. FROM THE ARPRORRIATE SAMPLING TUBE. 

Pneumatic cloth control In this system the movement of the control roller (swivel roller) is activated by a sensor paddle and a solenoid valve controlling the flow of compressed air into one of two bellows (one bellow on each roller end), which inflates to move the roller in one or the other direction, which aligns the cloth by moving one end of the roller forward or backwards to track the cloth back to its centred position on the filter. 

Keywords— Air pressure monitoring, air pump/motor control, solenoid valve control, low power portable medical equipment. 

Injection in the split mode is used for the analysis of concentrated solutions. The injection is performed at a high temperature, above the boiling points of the analytes and solvent. The sample is rapidly inserted in the injector where it is instantly vaporized and mixed with the carrier gas. A solenoid valve controls the proportion of the gas mixture (split ratio) that escapes through a leak. This procedure allows one to evacuate of part of the gas flow to decrease the amount of sample that enters the column, thus avoiding the saturation of the stationary phase (refer to Section 1.2.2.1). 

Titrations may be automated using a pump to deliver the titrant at a constant flow rate, and a solenoid valve to control the flow (Figure 9.5). The volume of titrant delivered is determined by multiplying the flow rate by the elapsed time. Automated titrations offer the additional advantage of using a microcomputer for data storage and analysis. 

Fig. 10. Use of solenoid valve for shutdown. Upon signal to shutdown, the solenoid closes a controller air signal port and opens a vent port.

Loop two or more elements where a signal passes between them for measurement and/or control, eg, sensor -i- transmitter -i- control + valve device two or more elements combined for a discrete state condition, eg, block valve -i- solenoid valve -i- actuator -I- limit switches... 

Solenoid Valves The electric solenoid valve has tw o output states. Wlien sufficient electric current is supplied to the coil, an internal armature moves against a spring to an extreme position. This motion causes an attached pneumatic or hvdraiilic valve to operate. Wlien current is removed, the spring returns the armature and the attached solenoid valve to the deenergized position. An intermediate pilot stage is sometimes used when additional force is required to operate the main solenoid valve. Generallv, solenoid valves are used to pressurize or vent the actuator casing for on/off control-valve application and safetv shutdown applications. 

Limit Switches and Stem-Position Transmitters Travel-limit switches, position switches, and valve-position transmitters are devices that, when mounted on the valve, actuator, damper, louver, or other throtthng element, detect the component s relative position. The switches are used to operate alarms, signal hghts, relays, solenoid valves, or discrete inputs into the control system. The valve-position transmitter generates a 4-20-mA output that is proportional to the position of the valve. 

Control of the compressor is achieved by engaging the required number of cylinders. In. say. a 16-cylinder compressor if we engage only four cylinders, the compressor will run at 25 7r capacity, and if w c engage eight cylinders, the compressor will run at. 5()C< capacity. Electrically operated solenoid valves are provided for capacity control. Energy can be conserved by using static controls, as discussed in Section 6.15. 

To control the room temperature llow of chilled w atei is controlled in AHU, Figure I 3.49(e). A thermostat senses the room condition and iictivates a motorised solenoid valve in AFIU coil which in turn adjusts the flow of... 

The unit shown on the next page in figure 4.4.1 is a somewhat simplified version of a tested, actual unit. The six gaseous feed components enter through check valves at a pressure regulated to about 4 atm higher pressure then experimental pressure, e.g., 22 atm. Six mass flow controllers set the flows and all but the nitrogen lines are secured with power to open solenoid valves (SV). 

Gas compressor anti-surge (GM-OFF) control circuit, comprising transmitters, computers and pneumatic control valve Reverse flow protection (on axnal compressors only) as supplementary protection device against surging, working independently of the control circuit Expander emergency stop valve with pneumatic actuator and solenoid valve... 

Solenoid valve actuator Electric motor, AC A Atmospheric outlet FC Control element closes on failure of auxiliary energy supply FO Control element opens on failure of auxiliary energy supply O Silencer... 

All valves are equipped with hydraulic actuators, electronic positioning controllers for precise positioning, and solenoid valves for rapid (trip) opening of bypass valves and emergency closure tripping of trip and inlet control valves. 

The actuating time for a quick-closing/quick-opening operation effected by the solenoid valves is 0.6 sec, and the actuating time under normal control is 5 sec for the inlet valves and 0.6 sec for the bypass valves. These actuating times apply to the full valve stroke outside the end position damping range. 

Remote Depressuring - A pilot operated valve is sufficiently positive in action to be used as a depressuring device. By using a hand valve, a control valve or a solenoid valve to exhaust the piston chamber, one can open the pilot-operated valve and close it at pressures below its set point from any remote location, without affecting its operation as a pressure relief valve. 

Since the low-pressure float needs a solenoid valve for tight closure, this valve can be used as an on-off control in conjunction with a pre-set orifice and controlled by a float switch (Figure 8.2). 

A low-pressure switch can also be used in conjunction with a thermostat and a solenoid valve in the pump-down circuit. In this method of control, the thermostat does not stop the compressor but de-energizes the liquid line solenoid valve to stop the supply of refrigerant to the evaporator. The compressor continues to run and pumps down the evaporator until stopped by the low-pressure switch. When the thermostat again calls for cooling, it opens the solenoid valve, liquid enters the evaporator and the low-pressure switch will close again to restart the compressor. This method is used to ensure that the evaporator is kept clear of liquid when the plant is off. If there is any leak at the solenoid valve, it will cause the... 

Figure 9.4 Solenoid valves, (a) Shut-off (Courtesy of Bailey Gill Products Ltd), (b) Change-over (Courtesy of Banco Controls Ltd)...

Solenoid valves are used in refrigeration and air-conditioning systems for refrigerant lines, oil pressure pipes (to control oil return and capacity reducers), and water and compressed air lines. Four-port changeover valves (Figure 9Ab) are used to reverse flow in defrosting and heat pump circuits. A de-energized expansion valve will act as a solenoid valve. 

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