What types of cylinders are there in reciprocating compressors?

(1) According to the cooling method, they can be classified into: air-cooled cylinders and water-cooled cylinders.

(2) According to the presence or absence of a rear cover, they can be classified into: open cylinder and closed cylinder.

(3) According to the combination of each component, they can be classified into: combined cylinders and integral cylinders.

(4) According to the number of compressed volumes, they can be classified as: single-stage cylinders and differential cylinders.

(5) According to the compression method of the cylinder, it can be classified into: single-acting cylinders and double-acting cylinders.

(6) According to whether there is a buffer volume or not, they can be classified into: cylinders without buffer volume and cylinders with buffer volume.

2. Under what circumstances should cylinder liners be used?

(1) The medium is so dirty that the lubrication on the cylinder surface deteriorates, and the cylinder mirror surface wears out quickly, requiring frequent replacement.

(2) There are special requirements for the material or heat treatment of the cylinder.

(3) To achieve the serialization of cylinders.

3. What are the different forms of valve arrangement for compressors?

There are three traditional forms of valve arrangement on the cylinder: configuration on the cylinder head, configuration on the cylinder block, and hybrid configuration. With the development of technology and the increase in demand, currently, the gas valves of some special compressors are arranged on the pistons.

4. What are the traditional forms of fixing the air valve of a compressor?

There are two forms: with an intermediate pressure cover and without an intermediate pressure cover.

5. What parts does the air valve consist of? What are the functions of each part?

The air valve is composed of a valve seat, a lift limiter, an opening and closing element (valve plate), and an elastic element (spring), which are connected and fixed with bolts.

Valve seat: It has an intake or exhaust air flow channel, forming a locked air flow state with the opening and closing motion elements. When the air valve is closed, it bears the pressure difference on both sides of the air valve.

Opening and closing element: It alternately and periodically opens and closes the valve seat airflow channel, usually made in sheet form and called a valve plate.

Elastic element: When the air valve is opened, it prevents the opening and closing movement element from colliding with the lift limiter at high speed. When it is closed, it promptly locks the opening and closing element in the valve seat channel.

Lift limiter: It limits the maximum opening height of the valve plate and also serves as the support seat for the elastic element.

The size of the valve plate lift has a direct impact on the compressor. The large lift makes the valve plate prone to impact, which affects the service life of the valve. The lift is small, the cross-sectional area of the gas channel is small, the resistance of the gas passing through is large, the exhaust volume is small, and the production efficiency is low. When adjusting the lift of the valve plate, for air valves without a regulating device, the valve plate elevation limiter can be machined. For air valves with a regulating device, the thickness of the spacer gasket inside the air valve can be adjusted.

When the elastic force of the spring is inconsistent, it will cause the valve plate to be skewed and stuck.

7. What are the different structural forms of air valves?

Under normal circumstances, air valves can be classified as :(1) Ring valves: ring valves, mesh valves; (2) Hole valves: Disc valves, cup valves, mushroom-shaped valves; (3) DC valve; (4) Reed valve :(5) Strip valve: Channel valve, self-spring strip valve.

8. What's the difference between an intake valve and an exhaust valve? What should be noted when installing the air valve? What problems will occur if the intake and exhaust valves are installed in reverse?

The valve seat of the intake valve is on the outside of the cylinder, while that of the exhaust valve is on the inside of the cylinder. Other parts are assembled according to the positions of the valve seats. When making a judgment, a screwdriver can be used for sensory inspection. For the suction valve, a screwdriver can push open the valve plate from the outside of the valve. For the exhaust valve, a screwdriver can be used to push open the valve plate from the inner side of the valve (note that when checking, apply gentle force to avoid damaging the valve plate).

9. Compared with metal valves, what are the advantages of non-metal valves?

Non-metallic valve plates are a type of air valve that emerged along with the development of engineering plastics. Due to the use of non-metallic materials with strong toughness to make the valve plates (rings), this type of air valve has unparalleled resistance to impurities, impact and oil viscosity compared to metal valves. It also has the advantages of a wide range of applicable working conditions and a long service life

10. Under what working conditions is it not advisable to use non-metallic valves?

Non-metallic valves should not be used in conditions with strong corrosiveness and large pressure differences. Oxygen compressors also cannot use non-metallic valves.

11. What should be noted when using non-metallic valves?

Non-metallic materials have certain limits of temperature and pressure resistance. When designing, the corresponding working conditions must be verified.

(2) Non-metallic valves generally cannot meet the requirements for determining whether they are leaking by using kerosene or water methods.

(3) In very rare cases, non-metallic valves have a brief running-in period after installation. During the running-in period, the exhaust temperature should not exceed the upper limit of the normal operating temperature of non-metallic materials (the upper limit of RF temperature is 120℃, that of MT and MC is 170℃, and that of PK and PC is 250℃).

(4) When storing non-metallic valve plates, please do not damage the sealed plastic bags. Keep them away from damp environments and place them horizontally on flat shelves. The valve plate itself should be protected from bending and deformation under heavy pressure, and the storage period should be controlled within one year.

12. Why is the kerosene test for gas valve leakage no longer widely applicable?

With the development of technology and the emergence of new materials and designs, the original use of kerosene to test the leakage of gas valves is no longer widely applicable, because:

(1) Non-metallic valve plate gas valves are very likely to fail the leakage test with kerosene. However, if they pass the air tightness test, there will be no problem when they are put into operation. The sealing of the valve plate is achieved by pressure difference. The air tightness test method precisely simulates this working characteristic and examines the sealing ability of the valve plate against gas when there is a pressure difference.

(2) For some air valves with special structures, such as lifting gaskets and other spacers between the valve plate and the valve seat, if kerosene is used for leak testing, the middle ring of the air valve will definitely leak.

(3) No air valve is absolutely leak-free. As long as the leakage is below the allowable value, it is qualified.

13. Why might excessive oil lubrication affect the working condition and lifespan of the air valve?

(1) Excessive lubricating oil increases the viscosity of the oil, causing the delayed closing of the air valve, higher energy consumption and greater impact.

(2) Excessive oil causes liquid hammer and damages the air valve.

(3) At high temperatures, lubricating oil may form coke and carbon deposits, which can cause gas valve leakage and valve plate breakage.

14. Why do factors such as liquid hammer, debris, and dust directly affect the lifespan of the gas valve?

Due to the incompressibility of liquids, when they are compressed, they will have an impact on the cylinder and piston, and at the same time damage the valve.

(2) Debris and dust, etc. will clog the channel and affect the free movement of the valve plate; at the same time, they will also cause impact on the air valve, leading to damage of the parts.

15. Is there any relationship between the probability of air valve damage and the operating time?

It is related. Usually, it is most dangerous between 0.5 and 200 hours after driving.

16. What is the most vulnerable component in the air valve?

The most vulnerable components in the air valve are the moving parts such as the valve plate and the spring.

17. Why are springs prone to breakage?

The main reasons for spring breakage are:

(1) Normal fatigue fracture occurs when the usage time exceeds its designed service life.

(2) The selection of spring material and spring force does not match the working conditions.

(3) The spring was not installed correctly during maintenance and assembly or there were defects in the spring itself.

(4) The new spring and the old spring are both installed in one air valve.

18. Why do valve plates often develop new cracks at the outermost circle?

When the pulsating airflow of a reciprocating compressor passes through the valve, it is prone to cause the valve plate to tilt. The impact velocity of the outermost circle of the valve plate is always the greatest, and the number of impacts is also the highest, thus it is also the most likely to be damaged prematurely.

19. How does corrosion affect the lifespan of air valves? Corrosion that occurs will affect the gas valve:

(1) The corrosion points on the surface of the valve plate directly lead to a decline in air tightness. Severe corrosion will reduce the strength of the valve plate and cause it to be damaged directly.

(2) Springs: Any degree of corrosion directly affects the strength and working characteristics of springs. Compared with valve plates, springs are more prone to corrosion damage. More than 50% of the valve plate damages are caused by the failure of the spring first, which then leads to an imbalance in the movement of the valve plate and excessive local impact, resulting in damage.

(3) When the valve seat and the valve cover, especially the sealing line of the valve seat, are corroded, their sealing performance is lost.