Piston Compressors
Operating Principles of Piston Compressors
The piston compressor was one of the earliest compressor designs, but it is still one of the most versatile and very efficient. In a piston compressor, a piston is moved forward in a cylinder by means of a connecting rod and a crankshaft. If only one side of the piston is used for compression, it is called a single-acting compressor. If both the upper and lower sides of the piston are used, it is called a double-acting type.
The piston compressor is very versatile and has almost no limitations. It can compress air as well as gas with little or no modification. The piston compressor is the only design capable of compressing air and gas to high pressures suitable for applications such as breathing air.
Configurations of piston compressors can range from single-cylinder configurations for low-pressure/small-volume applications to multi-stage configurations capable of compressing to very high pressures. In a multi-stage compressor, air is compressed in stages, increasing the pressure in each stage.
Compression capacity:
The CompAir piston compressor line is available in power ranges from 0.75 kW to 420 kW (1 hp to 563 hp), and produces working pressures from 1.5 bar to 414 bar (21 to 6004 psi).
Typical applications are:
Gas compression (CNG, nitrogen, inert gases, landfill gases)
High pressure air (breathing air for underwater respirator cylinders, seismic surveys, pneumatic circuits, etc.)
PET blowing, engine starting, industrial
Rotary screw
Rotary screw compressors. Principle of operation
Screw compressors are volumetric compressors with a piston in the form of a screw; this is the main type of compressor in use today. The main components of the screw compressor element are a convex rotor and a concave rotor, which move close to each other so that the volume between them and inside the chamber is gradually reduced. The pressure ratio of the screw type depends on the length and shape of the screw and the shape of the discharge port.
The screw element is not equipped with any valves, and there are no mechanical forces that create imbalances. This makes it possible to operate at high shaft speeds and to combine high flow rates with small external dimensions
Compression capacity:
The CompAir rotary screw compressor series is available in the power range from 4 kW to 250 kW (5 to 535 hp) and produces working pressures from 5 bar to 13 bar (72 to 188 psi).
Food, Beverage, Brewing
Military, Aerospace, Automotive
Industrial, Electronics, Manufacturing, Petrochemical
Medical, Hospital, Pharmaceutical
Instrumented Air
Rotary Slide Compressors
Rotary Slide Compressors Principle of Operation
The slide compressor is based on the traditional, proven, and proven principle of rotary slide compressors. Compressors utilize traditional, proven technology and are driven directly at very low speeds (1,450 rpm) for unparalleled reliability. The rotor, which is the only continuously running component, has a number of slots cut along its length in which slide blades are inserted that slide on a film of oil.
The rotor rotates in the stator of the cylinder. During rotation, centrifugal forces push the slides out of the slots, creating individual compression chambers. The rotation decreases the volume of the compression chamber and increases the air pressure.
The heat generated by compression is controlled by injecting pressurized oil.
The high-pressure air is discharged through an exhaust port, where the oil residue is removed by a final oil separator.
Compression capacity:
CompAir's sliding vane compressors are available in the power range of 1.1 kW to 75 kW (1.5 to 100hp) and produce working pressures of 7 to 8 and 10 bar (101 to 145psi).
Typical applications are:
OEM, printing, pneumatic
laboratory, dental, instrumentation
machine tools, packaging, robotics
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Failure phenomena:
1, winding short circuit, disconnection, and winding touch the shell grounded: These failures are caused by the compressor's motor part of the fault phenomenon disconnection of the power supply is normal, the compressor does not work; short-circuit and touching the shell of the power supply, or burn a fuse! Protector action, or burn fuses; it should be noted that if the winding turns slightly short-circuited, the compressor is still able to work, but the working current is very high, the compressor's temperature is very high, after a long time, the thermal protector will act. Winding short circuit and winding touching the chassis grounding general multimeter can be checked; winding short circuit, especially a slight short circuit, due to the winding resistance itself is very small, so it is not easy to determine, should be based on the measurement of current to determine.
2, the compressor shaft, card cylinder: compressor if the loss of oil or impurities into the often cause shaft or card cylinder, the failure phenomenon is that the compressor does not run after power, the protector action.
3, the compressor suction and discharge valve is not closed: If the compressor suction and discharge valve is damaged, even if the refrigerant is sufficient system can not establish a high and low pressure or difficult to establish a qualified high and low pressure, the system does not refrigerate or refrigeration effect is very poor.
4, the compressor vibration and noise: this kind of problem often occurs in the maintenance work, generally does not have much impact on the refrigeration performance, but will make the user feel abnormal, often caused by the pipeline and casing touching the compressor fixing bolts loose and vibration damping block off.
5, thermal protector damage: thermal protector is the compressor accessories, the fault is generally broken or action temperature point becomes small. Disconnect will cause the compressor does not work; action temperature point becomes small will cause the compressor to work for a period of time on the shutdown and repeated so, the problem is often easy to confuse with the winding turns slightly short-circuited, the difference is that the thermal protector is damaged when the working current is normal, short-circuited windings when the current is large.
Maintenance methods:
compressor motor part of the problem, the compressor suction and discharge valve is not closed tightly and the thermal protector failure should be taken to replace the approach.
Compressor holding shaft, stuck cylinder failure can first try to repair, the specific methods are as follows:
(1) knocking method:
Turn on the compressor with a wooden hammer knocking the lower part of the compressor, so that the compressor is stuck inside the parts of the compressor by the vibration of the running up.
(2) capacitor starting method:
You can use a capacitor with a larger capacity than the original into the circuit to start.
(3) high-voltage starting method:
You can use a voltage regulator to start the power supply voltage up.
(4) pressure relief method:
start after all the refrigerant of the system is drained.
If none of the above methods work, there is only replacement.
Compressor vibration and noise problems dealt with, should check and separate the parts that touch each other; check and tighten the compressor foot bolt, pay attention to the compressor's foot bolt can not be completely screwed to the end, the design requirements must maintain a gap of about 1mm, the maintenance process there will be compressor foot bolt screwed to death and cause the compressor violent vibration of the case; to check the vibration block whether to fall off, Whether to check the shock absorber block is off, whether to stick firmly *, you can also try to increase the shock absorber block, the specific location with the method of trying to post the effect of good there on the post there.
Compressor failure judgment and treatment:
1. How to identify the hermetic compressor housing on the three terminals? Run terminal (R), start terminal (S), public **** terminal (C), the resistance between RS is greater than the resistance between SC is greater than the resistance between RC. the resistance between RS is equal to the resistance between SC plus the resistance between RC. The use of the above laws can be identified. It should be noted that the three-phase compressor terminal resistance is equal. 2. how to determine the compressor motor winding short circuit? With a multimeter selected R × 1 gear, zero, measure the resistance of the compressor motor winding C-R or C-S two points. If the resistance value of the measured winding is less than the normal value, it can be judged that the winding is short-circuited. For three-phase motor, with two pens were contacted 3 terminal terminals in 2, if 3 times the measured resistance is the same, indicating that the winding is good; if there are 2 times the measured resistance to infinity, indicating that a group of windings out of circuit; if 3 tests are infinity, indicating that at least two groups of windings out of circuit; if 3 measurements of the measured resistance value of the 2 times is significantly smaller than the other measured, indicating that there is a short-circuit. 3. how to How to judge the compressor motor touching the shell through the ground? Compressor motor touching the shell through the ground is the winding wire internal wiring insulation damage and compressor shell touch, forming a short circuit. This failure can cause the fuse to blow and the compressor motor will not run. Check the method of touching the shell through the ground, you can also use the resistance of the multimeter. Zero first, and then put a pen and the common point of tightly against the firm, the other pen lap tight compressor process tube on the exposed metal part, or the shell plate of the paint skin support off a small piece, for measurement. If the resistance value is very small, you can judge the winding or internal wiring touching the shell through the ground. 4. how to judge the compressor motor winding disconnection? The multimeter will be adjusted to R × 1 gear, and then adjust the zero, the pen will be connected to the terminals of any two windings, measure the resistance value. If the winding value is infinity (∞), that is, between the terminals of the 2 windings do not lead to judge this winding is broken. 5. compressor does not start. (1) Check whether the compressor overload, pressure switch, overcurrent protector is open or damaged. (2) Check the indoor thermostat and tube thermostat, in the refrigeration state, whether open circuit or poor contact, in the heating state, whether short circuit. (3) Use a multimeter to check if the compressor relay is engaged. (4) Wiring error. (5) Compressor open or short circuit. (6) Bad compressor capacitor. (7) Bad AC contactor. (8) check whether the corresponding foot of the 2003 OV output, if there is OV, then the relay problem, if no OV output, but 11.5V output, then check whether the corresponding foot of the main chip 5V output, if there is, then the 2003 problem, if there is no, then the main chip problem. 6. overheating of the compressor, resulting in the start of a short period of time that is the shutdown (protector action), please check whether: (1) insufficient or excessive refrigerant Please make up the leakage and vacuum, add enough refrigerant or release the excess refrigerant. (2) The capillary tube assembly (including filter) is clogged, the suction temperature rises, please replace the capillary tube assembly. (3) Four-way valve internal air leakage, constitute false operation, confirm the damage and update. (4) The compressor itself is faulty, such as short circuit, broken circuit, touching the shell through the ground, etc., check and confirm the replacement of the compressor. (5) The protective relay itself fault, please use a multimeter to check in the compressor is not overheating its contacts whether the conductive, if not conductive to replace the new protector. When replacing 5528, 5532 compressor, need to check the start capacitor and start relay (if one of them is damaged, both must be replaced at the same time). (6) High-pressure pressure is too high, pressure relay action, please analyze the cause, for the situation to be eliminated. (7) Condenser is poorly ventilated or airflow is short-circuited, please remove the obstacles on the outside of the room and clean the condenser. (8) The system is mixed with non-condensable liquid gas (such as air, etc.), please evacuate and refill. (9) Compressor running current is too large, please find out the reason to be eliminated. (10) Outdoor unit ambient temperature is too high, please keep away from heat source and avoid sunshine. (11) Compressor jammed cylinder or hold shaft. Available rubber hammer or hammer pads on the wooden block knocking vibration compressor shell, or the use of parallel capacitors, discharge fluorine no-load method, may make the compressor start running, but if ineffective, you should replace the compressor. (12) The vapor-liquid valve is not fully open. 7. Judgment of low efficiency of the compressor. The reason for the decline in efficiency is due to wear and tear of moving parts, so that the fit clearance is too large, or suction and discharge valve rupture, or cylinder gasket asbestos plate breakdown caused by. Generally manifested as a drop in exhaust pressure, suction pressure increases, compressor cylinder head and suction and discharge chamber temperature is too high. If in the suction and discharge pipe mouth connected to the low-pressure table and high-pressure table, when the exhaust pressure of 0.6Mpa or more, the suction pressure remains in the 0Pa or can only reach the vacuum level of 52.5Pa or more, you can judge the compressor efficiency is low. 8 compressor loss of working capacity judgment. Refers to the compressor can operate normally, but has lost suction and discharge function. First compressor liquid process tube with scissors cut, such as a large number of R22 spray, you can judge is not due to leakage of R22 refrigeration. At this point, the compressor suction and discharge pipe with a torch melt off, remove the compressor, start the compressor alone, to be the compressor operation, the compressor with a sense of touch test suction and discharge pressure. Should first try the suction port with or without suction, and then, try the exhaust port with or without exhaust, with a hand blocking the exhaust port, such as feeling the pressure is not very large, or even no exhaust, the compressor can be considered to lose the ability to work. If the pressure is not very high, or even no discharge, the compressor is considered to be incapable of operation. 9. Why is the compressor motor current too high? (1) Compressor turn-to-turn short circuit, but not to the extent of blowing the fuse. (2) compressor "vice friction", destroying the friction surface finish, resulting in an increase in compressor power and current, but has not yet reached the "holding shaft" or "card cylinder", so that the compressor can not be The degree of rotation. Can use a multimeter to check the ground insulation resistance of the compressor motor, under normal circumstances should be more than 2MΩ, such as significantly smaller or close to zero, that has been short-circuited. If the insulation resistance to ground is normal, check the starting and running winding resistance value. If the turn-to-turn short-circuit, the operating current increases. 10. three-phase compressor motor startup difficulties in the cause of A. supply voltage is too low. B. compressor motor winding short-circuit. 11. how to troubleshoot the three-phase compressor motor in the operation of slow speed, a phase of the fuse blown, a phase of the current increases in the fault? The cause is often due to the compressor motor winding has a phase of touch shell through the ground caused by. After removing the ground wire, the test pen can be used to measure whether the case is charged. If the case is charged, and then unplug the power supply, touch the compressor case, the case should be localized in the hot feeling. Please rewind the compressor motor windings or replace the compressor. 12. How to eliminate the three-phase compressor motor in the operation of the "whirring" sound? The three-phase compressor motor makes a "whimpering" sound during operation, which is caused by a serious three-phase imbalance, and one phase of the power supply must be out of phase. Please check with the voltage of multimeter and restore three-phase. 13. How to rule out the reversal of three-phase compressor motor? It is caused by wiring error, any two wires can be interchanged. 14. Compressor replacement order and attention (1). The refrigerant (R22) used in air conditioners is a non-flammable gas, but if it comes into direct contact with a high-temperature flame, it will decompose and produce toxic gases. (If the pressure in the refrigeration system is too high, welding is very dangerous, and it is absolutely not possible to weld at this time). Therefore, before the welding operation, release the refrigerant in the refrigeration system slowly. (2). Determine the state of the lubricating oil condition of the refrigeration system Normal abnormal
Oil condition Color Light yellow Brown: refrigeration oil has deteriorated, caused by high temperatures Black: to produce abrasion or refrigeration oil is seriously carbonized Yellowish-green: there is moisture into the production of acid
Smell No Barbecue smell with irritation
(3). When discharging out the residual refrigerant, drain slowly, too fast will drain the lubricating oil from the compressor. If the compressor has burned out, it will vent out the toxic gas produced during thermal decomposition of the refrigerant, please pay attention to the operator. (4). After draining out the refrigerant, remove the electrical plugs and parts from the compressor. (5). Remove the welded parts of the high and low pressure connecting tubes (a protective layer may be used to prevent the sound insulation from being burned). (6). Remove the old compressor. (7). Pour out the compressor refrigeration oil to confirm the oil color; if the oil color is abnormal, the system should be cleaned. (8). Install new compressor. (9). Bend and shape the high and low pressure connecting tubes with a pipe bender and install the original rubber feet. (10). Braze the tube connections by brazing the work. (11). Connect compressor wires. To avoid incorrect wiring of terminal terminals, wiring must be made with reference to the wiring diagram. (12). Vacuuming the system. Sufficient pumping time is required to ensure system vacuum. (13). Fluoride filling and leak detection. Charge fluorine according to the standard amount of fluorine on the nameplate. 15. How to replace the scroll compressor? When replacing the scroll compressor, the high pressure side and low pressure side should be carried out at the same time when discharging the refrigerant, and it is forbidden to carry out the process only from the high pressure side, as the axial sealing of the scroll disk will cause the refrigerant to be retained in the low pressure side. Welding operations, in order not to generate an oxide film on the inner wall of the copper tube, must be passed into the nitrogen, nitrogen to the time to be sufficient, the test method for the nitrogen outlet placed on the other lit incense or cigarette, such as incense extinguished, it is shown that the air in the system are emptied, then you can carry out welding operations. Due to the use of scroll compressor requirements, prohibited in the replacement of the compressor or other parts of the compressor as a vacuum pump to empty the air in the pipeline of the outside unit, otherwise it will burn the compressor, you must use a vacuum pump to vacuum. System in the maintenance of the internal air collection, not allowed to reduce the pressure in the system to a vacuum state, only the pressure in the system can be operated at the gauge pressure of 0.03MP or more, otherwise it will lead to the compressor suction side of the scroll disk axial sealing the formation of a vacuum, the operation will be improperly damaged compressor. 16 scroll compressor air-conditioner using the removal of the matters needing attention? Scroll compressor is easy to be damaged when recovering refrigerant when moving the compressor, the reason is that the time of recovering refrigerant is too long, the compressor operates under vacuum for a long time, the compression ratio is large, and the temperature of the compressor rises sharply, resulting in burnt out. Therefore, the recovery of refrigerant time is not more than 3 minutes; or observe the changes in the low-pressure table, when the low-pressure table refers to the 0.03Mpa ~ 0.05Mpa, and then pumping for 20 to 30 seconds can be; or in the process of recovery of the abnormal sound is not more than 20 seconds after the shutdown. After moving and reinstalling the machine, test run, need to check the low pressure to find out whether the need to add fluorine, low pressure depending on the climate, temperature control between 0.45Mpa ~ 0.53Mpa. 17. air conditioner compressor overload protector which types? Air conditioner compressor overload protector mainly has 2 types: (1) external overload protector. The external overload protector is fastened to the compressor housing by means of a spring clamp. It is connected in series on the line used for the full current through the *** (e.g., a three-phase compressor should be connected to two of the three lines). When the compressor is overloaded or the ambient temperature when the air conditioner is running exceeds 43℃ or the compressor is started again less than 3min after shutting down, the overload protector cuts off the current and stops the compressor from running. The interior of the external overload protector consists of a bimetallic disk (bimetal), a contact point, a terminal and a heat-generating wire. Heat wire and bimetallic disk are installed inside the heat-resistant resin base (some overload protectors are only installed inside the bimetallic disk without heaters). When overcurrent or overheating, the bimetallic disk heat and deformation, so that the contact disconnect, cut off the current, play a role in protecting the compressor motor. When the bimetallic disk gradually cooled down to restore the original state, the contact is closed, connecting the current, so that the compressor resumes work. (2) buried overload protector. Embedded overload protector structure, its temperature-sensitive components directly feel the temperature rise of the motor winding. When the winding temperature rises above a certain value, it will cut off the circuit, so that the compressor stops working. When the winding temperature drops to a normal value, the protector turns on the power again and the compressor resumes operation. 18. What are the forms of protection devices for air-conditioner compressors? Air conditioner compressor is the most critical components of the refrigeration system, when the power supply voltage is abnormal or poor operating environment, often resulting in overloaded compressor operation, if there is no protection device for its protection, the compressor motor will be burned, the current commonly used protection devices have the following forms: (1) overload protector. Mainly used for compressor motor overcurrent and overheating protection. Overload protector shell and compressor shell surface close. For single-phase compressor motor, the protector should be connected in series in the full current through the *** with the line; for three-phase compressor motor, the protector should be connected in series in the three-phase line in the two lines. (2) Internal protector. Mainly used for single-phase compressor motor, series connected to the compressor internal motor winding *** on the same line, the compressor motor for overcurrent protection. (3) Thermal relay. Mainly used for three-phase compressor motor line overcurrent protection. Its two sets of coils connected in series in the three-phase line in two phases. When the overload current flows and reaches a certain time, its protection switch is disconnected. (4) reverse phase preventer. Mainly used for three-phase rotary compressor motor, protect the phase sequence of the three-phase power supply, in order to prevent the compressor from rotating in the opposite direction. In addition, it also has the function of phase loss protection.19. How does the air-conditioner compressor overload protector work? Generally overload protectors have 2 aspects of protection, startup and operation. When the compressor starts, due to mechanical failure to make the rotor "rolling brake", the current rises rapidly, when the current exceeds the rated value of the starting current, the protector contact jumped open, cut off the current, to avoid the motor start winding burned. In the normal operation of the compressor, due to external reasons caused by the temperature rise is too high or the current allowable value, the protector contact will also jump open, cut off the power supply, to avoid the motor running winding burned. 20. overload protector common faults? What are the causes? How to check and repair? The common faults of overload protector are: electric wire burning out, contact burning, contact disconnection after bimetal internal stress change can not be reset, buried overload protector insulation damage and contact failure, etc. The causes of overload are: overload protector, overload protector, overload protector, overload protector, overload protector, overload protector, overload protector, overload protector and so on. Causes of overload: (1) power supply voltage is too low, three-phase voltage symmetry is poor. (2) the compressor motor to extend the time of low-speed operation. (3) compressor motor long-term low-voltage operation with load. (4) Compressor motor cooling medium path is blocked. (5) Use of high ambient temperature. Check the overload protector can be carried out with a multimeter. Under normal circumstances, there should be tens of ohms resistance value, if the resistance value is infinity, indicating that the overload protector disconnected. Overload protector failure, in addition to poor contact, contact sticking can be repaired, other faults are generally not repaired, only for the replacement of updated processing. Buried overload protector failure, generally difficult to repair, but also not easy to replace, only with the compressor together for replacement. In the three-phase compressor motor, the use of three-phase overload protector mostly bimetal type. Bimetal elements and compressor contactor coil and low voltage (24V) line in series. The electric heating wire is connected in series with the compressor's contactor and motor connector (in the power circuit). The bimetal can open and close the compressor motor circuit when either overheating or overcurrent is sensed by the metal sheet. 21. What is liquid shock in a compressor? Air conditioner in normal working condition, the compressor suction back is refrigerant vapor rather than liquid, but due to the refrigerant charge too much or expansion valve adjustment flow is too large, so that the refrigerant in the evaporator is not completely evaporated, resulting in the refrigerant to the wet vapor or liquid state by the compressor suction back, resulting in the compressor of liquid shock. It will lead to the valve plate, valve plate, piston is broken broken, serious cases of connecting rod may also be deformed. When liquid strike occurs, the compressor will emit an abnormal sound, and at the same time, vibration will also occur. Liquid shock can occur if there is too much refrigerant in the refrigeration system or if the refrigeration oil is overcharged. Poor ventilation of the evaporator of the air conditioner, the cold carry away will make the evaporator frost or ice, which leads to low-pressure pressure is too low, can also cause the compressor shell frost and lead to liquid strike.