In the closed-circuit grinding operation, the grader that returns to the grinding machine for re-grinding is called sand returning. The ratio of the amount of sand returned to the original ore amount of the mill is called the return sand ratio and can be expressed as a percentage. Its calculation formula is as follows:
100(β-α)
C = ————————%
— — θ
Where C - return sand ratio, %;
Α—the yield of a specified fraction in the ore discharge of the mill, %;
Β——the yield of the above specified fraction in the overflow of the classifier, %;
θ - the yield of the above specified fraction in the sand return of the classifier, %.
After the ore discharge from the grinding machine, the sand returning from the classifier and the overflow sampling and analysis, and the values ​​of α, β and θ are obtained, the returning sand ratio can be calculated according to the above formula.

Valve Cover Gasket made of rubber or cork, its function is seals the top of the engine and prevents the oil leaks.
The color of Valve Cover Gasket usually is: Black, Gray, Blue, and Red- 

The rubber material of Valve Cover Gasket can be NBR(Nitrile Butadiene Rubber), ACM( ACrylate Material), SILICON AND VITON. Each type material have their own character: Consider the following characters when you choose the valve cover gasket: Vehicle types, oil-resistance, temperature-resistance, aging properties, costing and personal preference etc-

HAP VALVE COVER GASKET BASIC characteristic: 
Easy install.
Withstand high and low temperatures.
Provide the reliable sealing.
Use minimal tightening.

The new trend of valve cover gasket: 
These years, the new valve cover gasket are increasingly produced with profiles and not flat; that is, gasket surface is produced with beads or lips, Instead of the whole gasket surface, only the profile need to be pressed, So, the sealing beads or lips is very important, just a slight amount of bolting force can produces the sufficient deformation and adaptation. 


Valve Cover Gasket

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