Routine maintenance and troubleshooting of SMC solenoid valves SMC solenoid valves usually solve small flow control problems in two ways: (1) Special valve trims are used in standard SMC solenoid valves. This method can usually achieve Kv=0.03 or so. It is very economical and expandable to use special valve trim in the standard valve body, because it will reduce the requirements for special valve body and actuator spare parts. It is convenient for future expansion of the flow (only standard valve body parts need to be replaced in the future). (2) The special regulating valve designed for ultra-small flow adjustment can achieve a Kv value of about 0.001, has an approximate linear characteristic, is integrated for forging, is compact in structure and light in weight. How to choose a small pressure self-regulating valve A valve with a stable minimum pressure of 1 KPa is called a micro-pressure self-regulating valve. It is commonly used in propane gas and coke gas in steel plants, gas plants or chemical industries. In the past, most of these valves were imported, and the domestic market is still blank. However, at present, through the absorption and reference of foreign products, we have been able to solve this problem better. How to choose anti-cavitation high pressure regulating valve There are two main reasons for the short life of the high pressure valve: cavitation and erosion. Flashing, cavitation If the pressure difference (P1-P2) on the valve is greater than the maximum saturation pressure difference (Pmax) of the medium, flashing will occur, which will cause cavitation and damage to the internal and adjacent piping structure of the valve. The flow rate is maximized when the medium passes through the orifice with the smallest cross section. The increase in flow rate (or kinetic energy) is accompanied by a significant decrease in pressure (or potential energy). When the pressure is below the saturated vapor pressure of the medium, bubbles form in the medium. As the pressure at the orifice decreases further, bubbles form a large amount. There is no essential difference between flashing and cavitation at this stage, but the possibility of structural damage to the valve is certainly present. The reason for the leakage of SMC solenoid valve: air valve, the valve stem is too long and the valve stem is too short, the valve stem is not up (or down) enough, resulting in a gap between the valve core and the valve seat, which cannot be fully contacted. , resulting in a lack of strictness and leakage. SMC Solenoid Solution: The SMC solenoid valve stem should be shortened (or extended) so that the stem length is appropriate so that it is no longer leaky. Reasons for leakage of SMC solenoid valve packing leakage filler: (1) The packing is in close contact with the valve stem after loading the stuffing box, but the contact is not very uniform, some parts are loosely contacted, some parts are tightly contacted, and some parts are not in contact. (2) There is relative movement between the valve stem and the packing. As the medium with high temperature and high pressure and strong permeability is affected, the packing leaks. (3) The contact pressure of the filler is gradually attenuated, and the medium itself leaks from the gap due to the filler itself. solutions: (1) In order to facilitate the filling of the packing, the top of the stuffing box is chamfered, and a metal guard ring with a small erosion-resistant gap is placed at the bottom of the stuffing box to prevent the packing from being washed by the medium. (2) The contact surface of the stuffing box and the filler should be smooth to reduce the wear of the filler. (3) Flexible graphite is selected as the filler, which has the characteristics of good air tightness, small friction, small deformation, and no change in friction after retightening. Routine maintenance and troubleshooting of SMC solenoid valves 3, electric butterfly valve spool, core seat deformation leakage. The main reason for the leakage of the valve core and the valve seat is that the corrosion of the casting or casting in the production process of the electric butterfly valve can lead to the strengthening of the corrosion, and the passage of the corrosive medium and the erosion of the fluid medium will cause erosion of the valve core and the valve seat material. The impact causes the valve core and the valve seat to be deformed (or worn), and there is a gap and leakage. Solution: The valve core and valve seat are made of corrosion-resistant materials. If the wear and tear are not serious, it can be ground with fine sandpaper to eliminate the marks and improve the finish. If the deformation is serious, only the valve plug and the valve seat can be replaced. SMC solenoid valve failure The positioner adopts the nozzle baffle technology principle, and the following faults often occur frequently: 1) Parts are affected by temperature, vibration, etc., causing fluctuations in the mediation valve. 2) The nozzle is blocked by foreign matter and the positioner does not work properly. 3) The spring rate of the spring changes, causing the control valve to be non-linear. 4) The electrical interface is not well sealed, and the rain will short or open the positioner coil. Solution: Fix the positioner firmly; seal the electrical interface; improve the quality of the purified air and drain the drain regularly. SMC solenoid valve malfunction 1. The SMC solenoid valve has no action. SMC solenoid valve causes: insufficient air supply pressure; actuator failure; electric butterfly valve has no output signal; there is foreign matter in the valve; valve parts at high temperature are stuck. SMC Solenoid Solution: Check the air supply and restore the pressure; check the spring force of the actuator and the spring to break or the diaphragm is damaged (pneumatic valve); check the signal; disassemble the valve, check and repair. 2, the valve stroke is insufficient Cause: The positioner is not calibrated and the stroke is not adjusted properly; the actuator spring rating is too small; there is foreign matter in the valve. Solution: Re-adjust the positioner; adjust the spring; remove the valve to remove foreign objects. 3, the valve is slow Cause: The packing is too tight or the packing deteriorates; the valve stem is not straight, misaligned, causing large friction; the pressure of the air source is small. Solution: Restore the supply air pressure; replace the repaired packing or stem. Routine maintenance and troubleshooting of SMC solenoid valves Cab air conditioner,truck air conditioner, cabin air conditioner, engine driven air conditioning, engine power air conditioner XINXIANG HUATAI REFRIGERATION CO., LTD , https://www.trustht.com