Air Compressor
Leaky Intercooler
- leaky inter cooler of air compressor generally followed by the rupturing of bursting disc.
- Put the faulty compressor to manual and use the stand by compressor if available.
- Shut down the non-essential services so that the use of air can be minimized.
- Inform the bridge and ask to keep the movements as minimum as possible.
- The standby compressor if able to meet the air requirements, repair on the inter cooler can be carried out. Leaky tube can be plugged or brazing on the tube can be carried out. Followed by renewal of bursting disc.
- In case the standby compressor is not available then the faulty compressor needed to be kept operated.
- It should be taken care that the cooling water should not enter air side. For that water for the cooling of the inter cooler to be supplied only after staring the compressor and water supply to be stopped before stopping the compressor.
- Cooling water can be allowed to flow out of the ruptured bursting disc.
Troubleshooting
(A) collapse of discharge valve spring:-
i) over heated air or valve assembly.
ii) obstruction in valve operation due to dirt, dust or carbon deposition.
iii) Excessive moisture in the air.
iv) Lubrication is inadequate.
v) Fatigue fracture.
vi) Corrosion
Overheating of the valve can be due to the following reasons:-
- improper cooling of the air in the inter cooler. inter cooler may be dirty or have air trapped. Air side have oil/carbon deposition or water side have scale adhered. cooling water supply is not sufficient which can be due to partial opening of the valves or supply pump has lost efficiency.
- air can be over heated on repeated compression of the same volume. this is because of chocked suction filter or leakage discharge valves.
Valve operation may be obstructed because of the following reasons:-
-improper or excessive lubrication of the valve or the oil may got deteriorated.
- dirt or dust carried by air.
- scrapper rings are worn out.
B. Breakage of valve plates.
i) Running hours exceeded the maximum manufacturer recommended limit, causes the material of valve plate to become unfit for the service and result in breakage of the same.
ii) When not fitted properly with adequate torque or with improper copper gasket the valve will tend to flutter. Also excessive worn out of plate may cause the same effect, this will lead to breakage of the valve plate.
iii) When the valve is assembled incorrectly the valve plate will break.
iv) Deposits on the valve will make its operation sluggish which results in loss efficiency and make the compressor running hotter, will result in breakage of valve plates.
v) Valve plates break because of impact caused by breakage of valve springs or loss of their resilience.
(C) Over heating of the discharged air with an unrestricted air flow:-
since the air flow is unrestricted it can be assured that the valves and filters are in healthy state and are not causing the over heating of air.
Other reasons for the temperature rise of the air discharged can be fouling of inter stage coolers. the following reasons may reduce the efficiency of an inter cooler:-
- Improper cooling of the air in the inter cooler.
- Inter cooler may be dirty or have air trapped.
- Air side have oil/carbon deposition or water side have scale adhered.
- Cooling water supply is not sufficient which can be due to partial opening of the valves or supply pump has lost efficiency.
(D). Inoperative piston rings.
- Excessive worn out because of used after the running hours recommended by manufacturer.
-Improper lubrication, can be because of choked lube oil strainer or filter, because of loose belt of lube oil pump, because of low level of lube oil in sump. Or lube oil may got deteriorated.
- Poor size or material of the Piston ring used during last overhauling.
- Air flow is restricted because of the leaky valves, choked filters or partially closed valves in discharge line, causing the air to get over heated and rendering the lubrication of liner ineffective. compressor running hot.
- Excessive worn out of the liner and thus the rings are not sealing against the liner and air is leaking past the rings.
- improper maintenance, carbon deposition in the ring grooves may caused the sizure of the rings.
(A). Occasional lifting of 2nd stage relief valve.
I) Non-return valve in the discharge line of the compressor is stuck or clogged. Which providing a restriction in the flow of compressed air causing the relief valve in the second stage to lift occasionally.
II) H.P trip of the air compressor is set above the relief valve setting.
III) Main discharge valve of the air compressor is partially closed or being clogged.
IV) Relief valve is malfunctioning or the pressure setting of the valve is inappropriate.
(B). Breakage of valve plates.
i) Running hours exceeded the maximum manufacturer recommended limit, causes the material of valve plate to become unfit for the service and result in breakage of the same.
ii) When not fitted properly with adequate torque or with improper copper gasket the valve will tend to flutter. Also excessive worn out of plate may cause the same effect, this will lead to breakage of the valve plate.
iii) When the valve is assembled incorrectly the valve plate will break.
iv) Deposits on the valve will make its operation sluggish which results in loss efficiency and make the compressor running hotter, will result in breakage of valve plate
V) Valve plate break because of impact caused by breakage of valve springs or loss of their resilience.
(C). Puncture of Bursting Disc.
leakage of high pressure air form the tubes in the water side of inter-cooler can damage the body of inter-cooler, bursting disc is fitted on the inter-cooler which upon rapture releases the the high pressure to atmosphere and act as safeguard for the body of inter-cooler and compressor.
(D). Noticeable reduction in capacity of compressor over a period of time.
i) Clogged air suction filter will cause the less fresh air intake and re-expansion of the air in the bumping clearance. This will result in loss of compressor efficiency and will make the compressor running hot.
ii) Valve plate are dirty, damaged or worn out thus not sealing properly to achieve the required compression.
iii) Inadequate cooling of the inter-cooler, this is due to dirty tubes, scale formation in cooling surface on water side, oil or carbon deposition on air side, inadequate flow of the cooling water, or improper temperature of the cooling water.
iv) Air is leaking from various joints or gaskets, leakage form valve glands, un-loader drain valve sticky or leakage from the air bottle drain.
i) over heated air or valve assembly.
ii) obstruction in valve operation due to dirt, dust or carbon deposition.
iii) Excessive moisture in the air.
iv) Lubrication is inadequate.
v) Fatigue fracture.
vi) Corrosion
Overheating of the valve can be due to the following reasons:-
- improper cooling of the air in the inter cooler. inter cooler may be dirty or have air trapped. Air side have oil/carbon deposition or water side have scale adhered. cooling water supply is not sufficient which can be due to partial opening of the valves or supply pump has lost efficiency.
- air can be over heated on repeated compression of the same volume. this is because of chocked suction filter or leakage discharge valves.
Valve operation may be obstructed because of the following reasons:-
-improper or excessive lubrication of the valve or the oil may got deteriorated.
- dirt or dust carried by air.
- scrapper rings are worn out.
B. Breakage of valve plates.
i) Running hours exceeded the maximum manufacturer recommended limit, causes the material of valve plate to become unfit for the service and result in breakage of the same.
ii) When not fitted properly with adequate torque or with improper copper gasket the valve will tend to flutter. Also excessive worn out of plate may cause the same effect, this will lead to breakage of the valve plate.
iii) When the valve is assembled incorrectly the valve plate will break.
iv) Deposits on the valve will make its operation sluggish which results in loss efficiency and make the compressor running hotter, will result in breakage of valve plates.
v) Valve plates break because of impact caused by breakage of valve springs or loss of their resilience.
(C) Over heating of the discharged air with an unrestricted air flow:-
since the air flow is unrestricted it can be assured that the valves and filters are in healthy state and are not causing the over heating of air.
Other reasons for the temperature rise of the air discharged can be fouling of inter stage coolers. the following reasons may reduce the efficiency of an inter cooler:-
- Improper cooling of the air in the inter cooler.
- Inter cooler may be dirty or have air trapped.
- Air side have oil/carbon deposition or water side have scale adhered.
- Cooling water supply is not sufficient which can be due to partial opening of the valves or supply pump has lost efficiency.
(D). Inoperative piston rings.
- Excessive worn out because of used after the running hours recommended by manufacturer.
-Improper lubrication, can be because of choked lube oil strainer or filter, because of loose belt of lube oil pump, because of low level of lube oil in sump. Or lube oil may got deteriorated.
- Poor size or material of the Piston ring used during last overhauling.
- Air flow is restricted because of the leaky valves, choked filters or partially closed valves in discharge line, causing the air to get over heated and rendering the lubrication of liner ineffective. compressor running hot.
- Excessive worn out of the liner and thus the rings are not sealing against the liner and air is leaking past the rings.
- improper maintenance, carbon deposition in the ring grooves may caused the sizure of the rings.
(A). Occasional lifting of 2nd stage relief valve.
I) Non-return valve in the discharge line of the compressor is stuck or clogged. Which providing a restriction in the flow of compressed air causing the relief valve in the second stage to lift occasionally.
II) H.P trip of the air compressor is set above the relief valve setting.
III) Main discharge valve of the air compressor is partially closed or being clogged.
IV) Relief valve is malfunctioning or the pressure setting of the valve is inappropriate.
(B). Breakage of valve plates.
i) Running hours exceeded the maximum manufacturer recommended limit, causes the material of valve plate to become unfit for the service and result in breakage of the same.
ii) When not fitted properly with adequate torque or with improper copper gasket the valve will tend to flutter. Also excessive worn out of plate may cause the same effect, this will lead to breakage of the valve plate.
iii) When the valve is assembled incorrectly the valve plate will break.
iv) Deposits on the valve will make its operation sluggish which results in loss efficiency and make the compressor running hotter, will result in breakage of valve plate
V) Valve plate break because of impact caused by breakage of valve springs or loss of their resilience.
(C). Puncture of Bursting Disc.
leakage of high pressure air form the tubes in the water side of inter-cooler can damage the body of inter-cooler, bursting disc is fitted on the inter-cooler which upon rapture releases the the high pressure to atmosphere and act as safeguard for the body of inter-cooler and compressor.
(D). Noticeable reduction in capacity of compressor over a period of time.
i) Clogged air suction filter will cause the less fresh air intake and re-expansion of the air in the bumping clearance. This will result in loss of compressor efficiency and will make the compressor running hot.
ii) Valve plate are dirty, damaged or worn out thus not sealing properly to achieve the required compression.
iii) Inadequate cooling of the inter-cooler, this is due to dirty tubes, scale formation in cooling surface on water side, oil or carbon deposition on air side, inadequate flow of the cooling water, or improper temperature of the cooling water.
iv) Air is leaking from various joints or gaskets, leakage form valve glands, un-loader drain valve sticky or leakage from the air bottle drain.
Plate type valve overhauling
1. Prior to disassembling and assembling, prepare necessary tools.- Torques wrench
- Socket wrench
- Hexagon socket
- Screw driver
- Valve assembling jig
- Suitable box to house overhauled valve parts.
2. Maintenance and Inspection
1. Air valve: - Remove the valve (1st stage), suction valve (2nd stage) and delivery valve (2nd stage).
- Disassembling and reassembling procedure for suction valve (2nd stage) and delivery valve (2nd stage).
- Remove the valve (1st stage) stuck to the cylinder head by lightly hitting it with handle of hammer.
- Pay attention to the position and state of the valve seat gasket (1st stage) at reassembling.
- Do not damage the air valve seat. Do not assemble the plate and spring reversely. When reassembling the valve seat gasket (2nd stage), apply grease to prevent slippage, falling, and air leak.
1) Entire air valve
- Wipe out the air valve outside (both 1st and 2nd valves) with a clean cloth, and check deposit of carbon or sticking of foreign matters. Check for sticking of carbon and foreign matter.
- If carbon or foreign matter is stuck, disassemble the valve and carefully clean it with soft cloth or brush.
2) Valve plate
- Push the valve plate from the valve seat side using a driver or steel bar (3mm dia.), and check abnormality of valve plate face, and action of spring. Put the driver in several place to check action of the valve plate. The valve plate will make stroke equivalent to valve lift. Push the valve plate from the valve seat side.
- If the valve plate shows improper action, disassemble and clean it.
- If the valve plate is worn, replace it with new one.
3) Spring
- Disassemble the 1st stage side spring to check its damage or wear.
- Check the appearance of the 2nd stage side spring if there is no damage or wear.
- Replace the damaged or worn spring with new one.
3. Disassemble the valve as following:-
Before starting disassembling, clean up the surroundings to provide large space and prepare boxes to store the disassembled parts therein.
a. Clean especially around the thread of clamping bolt and nut by removing carbon and dirt accumulated.
b. Apply lube oil on to the cleaned thread
c. Clamp the fixing plate of jig by vice, then begin disassembling of valve.
d. Place valve on the assembling jig, put holder plate and flat washer on it. Then fix the valve by wing nuts tightened with finger force.
e. Loose valve clamping nut by socket wrench until it can be removed by finger force thereafter.
f. Take out valve from assembling jig, then overhaul it in prepared box.
- Socket wrench
- Hexagon socket
- Screw driver
- Valve assembling jig
- Suitable box to house overhauled valve parts.
2. Maintenance and Inspection
1. Air valve: - Remove the valve (1st stage), suction valve (2nd stage) and delivery valve (2nd stage).
- Disassembling and reassembling procedure for suction valve (2nd stage) and delivery valve (2nd stage).
- Remove the valve (1st stage) stuck to the cylinder head by lightly hitting it with handle of hammer.
- Pay attention to the position and state of the valve seat gasket (1st stage) at reassembling.
- Do not damage the air valve seat. Do not assemble the plate and spring reversely. When reassembling the valve seat gasket (2nd stage), apply grease to prevent slippage, falling, and air leak.
1) Entire air valve
- Wipe out the air valve outside (both 1st and 2nd valves) with a clean cloth, and check deposit of carbon or sticking of foreign matters. Check for sticking of carbon and foreign matter.
- If carbon or foreign matter is stuck, disassemble the valve and carefully clean it with soft cloth or brush.
2) Valve plate
- Push the valve plate from the valve seat side using a driver or steel bar (3mm dia.), and check abnormality of valve plate face, and action of spring. Put the driver in several place to check action of the valve plate. The valve plate will make stroke equivalent to valve lift. Push the valve plate from the valve seat side.
- If the valve plate shows improper action, disassemble and clean it.
- If the valve plate is worn, replace it with new one.
3) Spring
- Disassemble the 1st stage side spring to check its damage or wear.
- Check the appearance of the 2nd stage side spring if there is no damage or wear.
- Replace the damaged or worn spring with new one.
3. Disassemble the valve as following:-
Before starting disassembling, clean up the surroundings to provide large space and prepare boxes to store the disassembled parts therein.
a. Clean especially around the thread of clamping bolt and nut by removing carbon and dirt accumulated.
b. Apply lube oil on to the cleaned thread
c. Clamp the fixing plate of jig by vice, then begin disassembling of valve.
d. Place valve on the assembling jig, put holder plate and flat washer on it. Then fix the valve by wing nuts tightened with finger force.
e. Loose valve clamping nut by socket wrench until it can be removed by finger force thereafter.
f. Take out valve from assembling jig, then overhaul it in prepared box.
3. Assembling of valve:-
a). Check the necessary tools.
b). Apply new oil on to the thread clamping bolt and nut.
c). Place individual valve part one over another in correct order. Assemble them by tightening hexagon nut against clamping bolt temporarily with finger force.
d). Check the following:-
i. Outer face of valve guard and seat to be parallel.
ii. Retelling of valve guard against seat not to be seen.
iii. Valve guard to be securely positioned against seat by knock pin. It can be slightly turned by hand to radial direction within about 5° angle.
iv. Valve plate should leave freely from valve seat, i.e make lifting function without any obstruction. Check it by pushing valve plate with small screw driver though air passage channel of valve seat.
v. Place the valve made above mentioned checking on to the assembling jig fix it by tightening wing nuts with finger force.
vi. Tighten clamping nut with recommended tightening torque by using torque wrench.
vii. Take out valve from assembling jig. Then check for the free state of valve plate again. If no defect were found, assembling of valve is completed at this point.
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