A compressor is a driven fluid machine that promotes low-pressure gas to high-pressure gas, and is the engine of the gas source system. In use, it is inevitable that it will encounter various faults, which will seriously affect the work. In order to make it easier for everyone to find the cause for repair in case of failure, the following summarizes the common five types of faults based on the experience of air compressor repair, and analyzes the causes.
First, the amount of exhaust is insufficient
Insufficient exhaust is one of the most prone faults in compressors, and its occurrence is mainly caused by the following reasons:
01 Inlet air filter failure: fouling is blocked, so that the exhaust volume is reduced; the suction pipe is too long, the pipe diameter is too small, so that the suction resistance is increased, which affects the gas volume. The filter should be cleaned regularly.
02 Compressor speed reduction reduces the exhaust volume: improper use of air compressor, because the air compressor displacement is designed according to a certain altitude, intake temperature and humidity, when it is used in the plateau above the above standard When it is up, the intake pressure is lowered, and the amount of exhaust gas is inevitably lowered.
03 Cylinders, pistons and piston rings are worn out seriously and are out of tolerance, which increases the relevant clearance and increases the leakage, which affects the displacement. When it is normal wear, it is necessary to replace consumable parts in time, such as piston rings. If the installation is not correct and the gap is not suitable, it should be corrected according to the drawings. If there is no drawing, the empirical data may be obtained. For the circumferential gap between the piston and the cylinder, such as the cast iron piston, the clearance value is the cylinder diameter. 0.06/100～0.09/100; for aluminum alloy pistons, the clearance is 0.12/100~0.18/100 of the diameter of the gas path; the steel piston can take the smaller value of the piston of the aluminum alloy.
04 The stuffing box is not strict, and air leakage is generated to reduce the gas volume. The reason is firstly that the stuffing box itself is not required to be manufactured; the second reason may be that the piston rod and the stuffing box center are not well aligned during installation, causing air leakage due to wear and strain; generally, lubricating oil is added to the stuffing box. It can function as lubrication, sealing and cooling.
05 The influence of the compressor suction and exhaust valve failure on the displacement. Metal fragments or other debris are dropped between the valve seat and the valve plate, resulting in poor closure and leakage. This not only affects the amount of exhaust, but also affects the change in inter-stage pressure and temperature. This problem may be due to manufacturing quality problems such as valve warpage, and second, due to valve seat and valve wear. Severe and leaking.
06 The valve spring force is not well matched with the gas force. If the elastic force is too strong, the valve plate will be opened slowly, and if the elastic force is too weak, the valve plate will not be closed in time. This not only affects the air volume, but also affects the increase of power and the life of the valve disc and the spring. At the same time, it also affects changes in gas pressure and temperature.
07 The pressure of the compression valve is improper. If the pressing force is small, it will leak air. Of course, it will not be too tight, which will deform and damage the valve cover. The general pressing force can be calculated by the following formula: p=kπ/4 D2P2, D is the diameter of the valve cavity, and P2 is the maximum gas. Pressure, K is a value greater than 1, generally taking 1.5 to 2.5, K = 1.5 to 2.0 at low pressure, and K = 1.5 to 2.5 at high pressure. This is K. Practice has proved to be good. If the gas valve is faulty, the valve cover will inevitably heat up and the pressure will not be normal.
Second, the pressure is not normal
If the volume of gas discharged from the compressor does not meet the flow requirements of the user at the rated pressure, the exhaust pressure must be reduced. At this point, I had to change another machine with the same exhaust pressure and a large exhaust volume. The main reason for the abnormal pressure between the stages is the leakage of the gas valve or the leakage of the piston ring. Therefore, the reasons and measures should be taken from these aspects.
Third, the temperature is not normal
An abnormal exhaust temperature means that it is higher than the design value. Theoretically, the factors affecting the increase in exhaust gas temperature are: intake air temperature, pressure ratio, and compression index (for air compression index K = 1.4). The actual situation affects the factors of high suction temperature, such as: low intermediate cooling efficiency, or the scale connection in the intercooler affects heat transfer, the inhalation temperature of the latter stage must be high, and the exhaust temperature will be high. In addition, the gas valve leaks and the piston ring leaks, which not only affects the rise of the exhaust gas temperature, but also changes the interstage pressure. As long as the pressure ratio is higher than the normal value, the exhaust gas temperature will rise. In addition, water-cooled machines, lack of water or insufficient water, will increase the temperature of the exhaust.
Fourth, abnormal noise
If some parts of the compressor fail, an abnormal sound will be emitted. Generally speaking, the operator can discern the abnormal sound. The clearance between the piston and the cylinder head is too small and directly impacts; the piston rod and the piston connecting nut are loose or tripped; the piston end is blocked by the wire, the piston moves up against the cylinder head; the metal fragments in the cylinder and the accumulated water in the cylinder, etc. Both can make a knocking sound in the cylinder. Crankshaft bolts, nuts, connecting rod bolts, crosshead bolt loosening, tripping, breaking, etc. in the crankcase, the shaft diameter is seriously worn, the clearance is increased, the clearance between the crosshead pin and the bushing is too large or the wear is serious, etc. A percussion sound is heard in the crankcase. The venting valve piece is broken, the valve spring is soft or damaged, and the load regulator is improperly adjusted, etc., and the knocking sound can be emitted in the valve cavity. This is to find faults and take measures.
Five, overheated fault
In the friction between the crankshaft and the bearing, the crosshead and the slide, the packing and the piston rod, the temperature exceeds the specified value and is called overheating. The consequences of overheating: one is to speed up the wear of the friction pair, and the other is that the heat of the excessive heat accumulates and burns the friction surface and causes a major accident. The main causes of bearing overheating are: uneven bearing or journal contact or too small contact area; bearing deflection crankshaft bending, lubricating oil viscosity is too small, oil circuit is blocked, oil pump is faulty, resulting in oil cut, etc.; There is no gap, the spindle and motor shaft are not aligned, and the two axes are tilted.
Through the understanding of the compressor failure, we can solve the problem and reduce the loss in time when the fault occurs. Of course, these are just common faults. If they are not solved in the maintenance of the air compressor, they can be replaced or sent for repair.
