What happens when bumping clearance is excessive?
If the bumping clearance is large the extra clearance would result in a small volume of air being re-expanded every time causing increase in air temperature, fall in efficiency and overheating of the compressors. This would endanger the ship during maneuvering by sudden loss of propulsion.
What will happen if there is no bumping clearance?
The bumping clearance must be adjusted properly otherwise there is risk of damage and loss of efficiency. If the bumping clearance is less the volumetric efficiency would increase but there is risk of the piston hitting the cylinder head, especially when the compressor is unloaded during start and stopping.
What is clearance volumetric efficiency?
Simply defined, volumetric efficiency is the ratio of the amount of refrigerant gas entering the compressor (suction) versus the amount of gas leaving the compressor (discharge). This volume of gas (clearance volume) reduces the overall volumetric efficiency incrementally as it grows.
What is clearance ratio in compressor?
It is the ratio of clearance volume to the swept volume C = V c V s. This ratio has value in general between 4% to 10% The clearance volume is that volume which remains in the cylinder after the piston has reached the end of its inward stroke.
Why small clearance is required?
Clearance is the volume remaining in a cylinder end when the piston is at the end of its stroke. End clearance is required to keep the piston from striking the compressor head or crank end. Some small clearance is also required under suction and discharge valves so that the valves can be removed and reinstalled.
What is clearance ratio formula?
The renal clearance ratio is a measure of the speed at which a constituent of urine passes through the kidneys. It is defined by following equation: X is the analyte substance. Cx is the renal plasma clearance of X. Cin is the renal plasma clearance of inulin.
How do you calculate clearance volume?
Because of the irregular shape of the combustion chamber (volume in the head) the clearance volume is calculated empirically by filling the chamber with a measured amount of fluid while the piston is at TDC. This volume is then added to the displacement volume in the cylinder to obtain the cylinders total volume.
Why clearance volume is given?
Clearance volume or bumping clearance is the space between the top of the piston and the cylinder head of an air compressor. This clearance is an important aspect of the compressors and should be as less as practically possible to improve the volumetric efficiency of the compressor.
How is tappet clearance calculated?
Tappet clearance is adjusted after opening the lock nut above the rocker arm. This lock nut restricts the movement of tappet to ensure proper clearance setting. Open the nut using spanner of appropriate size ( Normally Ring Spanner are Used). Once the locknut is disengaged; tappet is free to move up and down.
How do you measure tappet clearance?
How To Check Tappet Clearance
- Taking all safety precautions.
- Make sure the piston is on TDC.
- Make sure the engine has cooled down.
- Loosen the lock nut of the rocker arm.
- Now adjust the tappet clearance between the rocker arm & valve stem by tightening or loosing the nut below the lock nut.