The diaphragm pump is also known as the control pump, which is the main type of actuator. By accepting the control signal output by the adjusting control unit, the fluid flow can be changed by means of dynamic operation. Diaphragm pumps are usually made up of actuators and valves. Using compressed air as the power source, for all kinds of corrosive liquid, with particles of liquid, high viscosity, volatile, flammable, highly toxic liquid, all can be pumped out.
The pneumatic diaphragm pump has four kinds of materials: aluminum alloy, cast iron, plastic, stainless steel. Electric diaphragm pump has four kinds of material: aluminum alloy, cast iron, plastic, stainless steel. According to different liquid media, the diaphragm pump is made of nitrile rubber, neoprene rubber, fluorine rubber, polyvinylidene fluoride and polyethylene. To meet the needs. In various special occasions, it is used to pump the medium that the conventional pump cannot pump.
1. Precautions for operation of diaphragm pump:
(1) the diaphragm pump operates a stainless steel self-priming pump.
Diaphragm pump is driven by frequency conversion motor, if open parking load is too big or too small, short run trickling water han brake legal wash out 3 て zhang on the wall through han just recite machinery Que Yong apricot colophon level member is dubious light? To avoid the occurrence of the above situation, hard and fast rules open parking load are controlled at about 30%, and set in the instrument that increase or decrease the load must be for a period of time to complete, effective from craft to do the maintenance of the inverter.
(2) operation of diaphragm pump instrument air and lubricating oil pressure system.
Diaphragm pump instrument air and is interlocked with main motor is equipped with the lubricating oil pressure, promote the filling and emptying valve of liquid to gas valve closed, always maintain a certain air pressure, the minimum of two valve pressure not less than 0.4 MPa, so instrument air pressure generally remain above 015 MPa, even after stopping the pump will not stop instrument air, so as not to promote liquid enough or too much fluid cavity, the air supply valve is filtered and oil atomization.
Diaphragm pump in operation, the lubricating oil pressure should not under pressure (0115 mpa), interlocking values and oil export filter differential pressure cannot too big, lubricating oil flow in the looking glass ball should be in the upper limit position, adjust the flow adjusting amplitude cannot too big, lest the instantaneous flow through ambassador pressure fall so fast interlock trip.
Through the above process improvement and mastering of operation point, make the diaphragm pump run time always has a stable process environment, running for more than a year, only a vehicle for electrical reasons, did it, safe and efficient operation for a long period of time.
Ii. Type of diaphragm pump:
Diaphragm pump by their ticket enforcement agencies use the power, can be divided into pneumatic, electrical, fluid movement three, namely to compressed air to power sources pneumatic diaphragm pump, based on electric power electric diaphragm pump, as a liquid medium (such as oil) pressure as the power of electric hydraulic diaphragm pump, in addition, according to its function and feature points, and electromagnetic valves, electronic style, smart, the total linear diaphragm pump, etc. There are many types of diaphragm pumps, and the structure is varied and constantly updated and changed. In general, valves are generic and can be matched to pneumatic actuators or to electric actuators or other actuators.
Iii. Selection of diaphragm pump type:
1. Selection of valve body type of diaphragm pump.
The selection of valve body is the most important part of diaphragm pump selection. There are many kinds of diaphragm pump valve body, which are commonly used in 10 kinds, such as straight single seat, straight double seat, Angle, diaphragm, small flow, three-way, eccentric rotation, butterfly, sleeve type, ball and so on. Before you choose the valve, the control process of medium, the careful analysis of process conditions and parameters, collect enough data, understand the requirement of system of diaphragm pump, according to the collected data to determine the valve type to be used. In the specific selection, the following aspects can be considered:
(1) the shape structure of the valve core is mainly considered according to the selected flow characteristics and unbalanced force.
(2) wear resistance when the fluid medium is a suspension with a high concentration of abrasive particles, the valve core and the seat joint surface will be severely affected by each shutdown. Therefore, the flow of the valve should be smooth and the internal material of the valve should be hard.
(3) corrosion resistance due to the corrosive medium, in the case of meeting the adjustment function, choose the simple structure valve.
(4) when the temperature and pressure of the medium are high and the pressure is high, the valve core and seat material shall be selected by the valve with small change in temperature and pressure.
(5) prevent flash and cavitation flash and cavitation only in liquid media. In the process of practical production, flash and cavitation effect not only the calculation of flow coefficient, still can form the vibration and noise, make the valve life is short, so when choosing the valve should prevent the valve from flash and cavitation.
2. Selection of diaphragm pump.
The action of the diaphragm pump is only available when the pneumatic actuator is selected, and its action is formed through the combination of the positive and negative effects of the actuator and the valve. There are four kinds of combinations are (closed type), positive and negative (gas) type, anyway (gas) type, reflect (gas close type), formed by the four combinations of diaphragm pump have spirit way on and off two. The selection of the mode of diaphragm pump is mainly considered in three aspects: a) production safety; B) characteristics of the medium; C) ensure product quality and minimize economic loss.
3. Selection of flow characteristics of diaphragm pump.
Flow characteristics of the diaphragm pump is refers to the relative flow and displacement of medium flow through the valve (relative opening degree of valves), the connection between the ideal flow characteristic mainly has straight lines, such as percentage (log), parabolic and quick opening, etc. 4. The commonly used ideal traffic characteristics are straight line, equal percentage (logarithm), and fast open three kinds. Parabolic flow characteristic between straight line and equal percentage, the percentage of properties such as generally available to replace, and quick opening feature is mainly used for two control and program control, so the choice of diaphragm pump characteristic is, in fact, the choice of straight lines and equal percentage flow characteristics.
The selection of flow characteristics of diaphragm pump can be calculated theoretically, but the methods and equations are complicated. At present, the empirical criterion is adopted, which is considered from the following aspects: the adjustment quality analysis and selection of the regulation system; To consider the situation of process piping; Analysis from load variation.
Choose good diaphragm pump flow characteristic, can according to the traffic characteristics determine the shape and structure of the valve core, but for like a diaphragm valve, butterfly valve, etc., due to their structural characteristics, can not change the surface shape of valve core to achieve the required flow characteristic, at this time, but by changing the feedback of the valve positioner CAM contour.
4. Selection of diaphragm pump actuator.
(1) output force considerations.
Actuator regardless of type, the output power is used to overcome the effective of load (mainly refers to the unbalanced force and unbalanced torque and friction, sealing force, gravity and so on) the action of forces. Therefore, in order for the diaphragm pump to work properly, the actuator should be able to produce enough output force to overcome various resistance and ensure the high seal and valve opening.
For dual - acting pneumatic, hydraulic and electric actuators, there is usually no reset spring. The magnitude of the force is independent of its direction, so the key to selecting an actuator is to find out the maximum output force and the torque of the motor. For single acting pneumatic actuators, the output power is associated with the opening of the valve, the force on the diaphragm pump will also affect the movement characteristics, therefore needs to be established throughout the opening scope of diaphragm pump force balance.
(2) determine the type of actuator.
After determining the output force of the actuator, the corresponding actuator should be selected according to the requirements of the process. When there are explosion-proof requirements on site, the pneumatic actuator should be chosen, and the junction box is explosion-proof, and the electric actuator can not be selected. If there are no explosion-proof requirements, the pneumatic and electric actuators can be selected, but the electric actuator should be selected as far as possible from the energy saving. For hydraulic actuator, its use is not as wide as that of pneumatic and electric actuator, but it has the characteristics of high precision, fast speed and smoothness, so in some cases; In order to achieve better adjustment effect, the hydraulic actuator must be selected, such as the speed regulation of the power plant transparent machine and the temperature regulation control of the catalytic device reactor in the refinery.
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