[Piston Compressor]Features of Piston Refrigeration Compressor When the piston moves to the right, the pressure in the left cavity of the piston in the cylinder is lower than the atmospheric pressure pa, the suction valve opens, and the outside air is sucked into the cylinder. This process is called the compression process. When the pressure in the cylinder is higher than the pressure p in the output air line, the exhaust valve opens. The compressed air is sent to the air pipe, and this process is called the exhaust process. The reciprocating motion of the piston is formed by the crank-slider mechanism driven by the motor. The rotary motion of the crank is converted into sliding – the reciprocating motion of the piston.
Classification of piston compressors
Piston air compressors are generally classified into exhaust pressure, exhaust volume (volume flow), structural type and structural characteristics sort.
1. According to the level of exhaust pressure, it is divided into:
Low pressure air compressor exhaust pressure≤1.0MPa
Medium pressure air compressor 1.0MPa<Exhaust pressure≤10MPa
High pressure air compressor compressor 10MPa<discharge pressure≤100MPa
2. The size of the exhaust volume is divided into:
Small air compressor 1m3/min<displacement volume≤10m3/min medium air compressor 10m3/min<displacement volume≤100m3/min
Large air compressor displacement>100m3/min
Air compressor displacement refers to the free gas flow in the suction state.
General regulations: Shaft power < 15KW, exhaust pressure ≤ 1.4MPa is a micro air compressor.
3. According to the relative position of the cylinder center line and the ground, it is divided into:
Vertical air compressor – the cylinder center line is arranged vertically to the ground. z
Angle air compressor – the center line of the cylinder forms a certain angle with the ground (V-type, W-type, L-type, etc.).
Horizontal air compressor – the center line of the cylinder is parallel to the ground, and the cylinder is arranged on one side of the crankshaft.
Dynamically balanced air compressor – the center line of the cylinder is parallel to the ground, and the cylinders are symmetrically arranged on both sides of the crankshaft./ X
4. According to structural characteristics, it is divided into :
Single acting – gas is compressed on one side of the piston only.
Double acting – gas is compressed on both sides of the piston. , F. H2 s; c0 z7 B
Water-cooled—means that the cylinder has a cooling water jacket and is cooled by water.
Air-cooled – the outer surface of the cylinder is cast with cooling fins for air cooling.
Fixed – the air compressor unit is fixed on the foundation.
Mobile – The air compressor unit is placed on a mobile device for easy transport.
Oil lubricated – refers to the oil injection lubrication in the cylinder, and the lubricating oil circulation lubrication of the motion mechanism.
Oil-free lubrication—means that the cylinder is not lubricated with oil, the piston and cylinder are dry running, but the transmission mechanism is lubricated by lubricating oil. All oil-free lubrication – the transmission mechanism in the cylinder is not oil-lubricated.
In addition, it is also divided into crosshead (small and medium oil-free air compressor), without crosshead (V, W type low pressure miniature air compressor); single-stage compression, two-stage or multi-stage compression.
Advantages and disadvantages of piston air compressors
The advantages of piston air compressors are simple structure, long service life, and easy to achieve large capacity and high pressure output. The disadvantage is that the vibration is large, the noise is large, and because the exhaust is intermittent, the output has pulses, and an air storage tank is required.
Operating Points of Piston Air Compressor
1. Preparations before starting
(1 ) Open the cooling water inlet valve and check whether the water supply to the cylinders of the coolers at all levels is normal. (2) Check whether the oil level in the crankcase is at the specified position. (3) Check whether the inlet regulating valve is closed, whether the outlet vent valve of the air compressor is open, and whether the air supply valve is closed. (4) Whether the electrical equipment is in the starting position. (5) Check whether the anchor screws and coupling screws are loose. (6) Turn the flywheel several times to check whether the flywheel is stuck.
2. Startup steps
(1) Turn on the power, start the air compressor, and pay close attention to whether the oil pressure is normal and whether there is any abnormal sound . (2) If everything is normal, open the inlet regulating valve. to fully open. (3) Gradually close the outlet vent valve. When the load of the air compressor is running normally, the air supply valve can be slowly opened to supply air.
3. Selection of air compressor installation site
The most neglected by the staff, often after the purchase of the air compressor, they will find a place at will, It is used immediately after piping, and there is no prior planning at all. However, such a sloppy result will lead to the failure of the air compressor, maintenance difficulties and poor air quality in the future. Therefore, a proper installation site is a prerequisite for the correct use of the air compressor system:
(1 ) Choose a spacious place with good lighting to facilitate the space and lighting required for operation, maintenance and repair.
(2) Choose a place with low air humidity, less dust, fresh air and good ventilation, and avoid water mist, acid mist, oil mist, dusty and fibrous environment.
(3) According to the requirements of GB50029-2003 “Code for Design of Compressed Air Station”, the heating temperature of the machine room of the compressed air station should not be lower than 15℃, and the temperature of the machine room during non-working hours should not be lower than 5℃ .
(4) When the air inlet of the air compressor or the cooling air inlet of the unit is set indoors, the indoor ambient temperature should not be greater than 40℃.
(5) If the factory environment is poor and there is a lot of dust, pre-filter equipment must be installed to ensure the service life of the air compressor system parts.
(6) When the air displacement of a single unit is equal to or greater than 20m3/min and the total installed capacity is equal to or greater than 60?m3/min, lifting equipment for maintenance should be installed. The weight capacity should be determined according to the heaviest part of the air compressor unit.
(7) Reserve passage and maintenance space. According to the requirements of GB50029-2003 “Code for Design of Compressed Air Station”, the width of passage between the air compressor unit and the wall is 0.8～ 1.5m distance.
Piston Compressor Troubleshooting
Fault 1: When starting, the motor hums, but the compressor does not startFuse blown Circuit breaker tripped?
Reason 1: The size of the extension cord is too low. Correction: Use a higher gauge wire to check the breaker fuse;
Cause 2: There are too many lights or appliances to be used in the line used by the compressor (the line is over-wired) Correction: Use another line or remove it Load in the line;
Cause 3: Check valve failure. Correction: Repair or replace;
Cause 4: The voltage is too low. Correction: Check with a voltmeter;
Reason five: The temperature is too low. Correction: Warm up or use light lubricating oil;
Cause 6: Incorrect fuse or switch size. Correction: Check and replace;
Cause 7: Poor ventilation and high indoor temperature. Correction: Move the compressor to a ventilated area;
Cause 8: The pressure switch is faulty. Correction: Replace the pressure switch.
Trouble Two: Compressor not working?
Reason 1: The power line is not connected. Correction: Plug in the power plug;
Cause 2: The pressure switch is in the off position. Correction: the switch is set to [Auto/On];
Cause 3: There is no lubricating oil in the compressor body (may seriously endanger the compressor) Correction: Refuel;
Cause 4: The belt is too large loose or too tight. Correction: Adjustment.
Fault 3: Wrong direction of rotation?
Reason: The motor cable is connected incorrectly. Correction: Change the line.
Fault 4: The compressor is overheated, and the motor is overheated?
Reason 1: The operating pressure is too high and overloaded. Correction: reduce the operating pressure;
Cause 2: The air filter or valve is blocked by carbon deposits. Correction: Remove for cleaning;
Cause three: Belt is too tight or centerline is not aligned. Correction: readjust, align;
Cause 4: The ambient temperature is too high or the ventilation is poor. Correction: Move to a well-ventilated place;
Cause 5: The voltage is too low or the wire is too long. Correction: replace the wire and add a voltage stabilizer.
Fault 5: The pressure cannot rise to the specified value?
Cause one: Valve assembly failure. Correction: overhaul, replace;
Cause 2: The safety valve is leaking. Correction: overhaul, replace;
Cause 3: Air leakage at the connection part. Correction: overhaul, adjustment;
Cause 4: Piston ring wear. Correction: Replace piston rings.
Fault 6: Too much noise?
Cause: Lack of lubricating oil in the crankcase. Correction: Check whether the bearing is damaged and refuel;
Cause 1: The motor belt guard of the pulley body is loose. Correction: Turn off the machine and re-tighten it;
Cause 2: Carbon deposits on the valve or piston. Correction: Remove the compressor cylinder head for inspection;
Cause 3: Bearing piston pin thrust bearing. Correction: Send to an approved service center for inspection.
Fault 7: Vibration?
Cause one: The pulleys are misaligned or too loose. Correction: Re-align or fix;
Cause 2: Bent (deformed) crankshaft Correction: Send to an approved service center;
Cause 3: Belt loose. Correction: Adjust the belt;
Cause 4: The ground is uneven. Correction: Flatten the ground.
Fault 8: Too much lubricating oil consumption or lubricating oil in the hose
Cause 1: Piston ring wear. Correction: Send to service center for replacement;
Cause 2: Cylinder leakage. Correction: Replace the cylinder;
Reason 3: Run-in Correction: Re (run-in).
