Mid-Point Test Sieves
We can supply you various types of mid point test sieves for your choice.
What Is A Mid-Point Sieve?
A mid-point test sieve has had the mesh inspected. The sieve is then selected as a mid-point if the results give tolerances that are in the middle of the ASTM Standard. For example, the ASTM permissible variations for the mesh of a No. 40 sieve (425µ) are:
- Average Opening ±19µ.
- Opening Dimension of 396µ not exceeded by more than 5% of the openings.
- maximum individual opening 502µ.
The mid-point would have a variation in Average Opening of ±9.5µ, opening dimension of 396µ not exceeded by more than 2.5% of the openings and a maximum individual opening of 463.5µ. The effect of this tightened tolerance is an improvement in variation of approximately 30%. These results are traceable to a NIST standard.
Where should mid-point sieves be used?
When a process requires a high level of repeatability, mid-points can be used on all sieve tests. However, the predominant application for the mid-point sieves is as master stack. A master stack is used to check and recalibrate sieves used in everyday testing. It can be also used for the screening of sand.
If your process must have traceability and the precision and repeatability of your sieve testing results is critical to your process or customer requirements, Mid-Point sieves should be considered for the master stacks and for every day testing of supercritical processes.
Let us serve you
We are the leading manufacturer of test sieves products in China. We provide you with high quality products and considerate service. Become our customers and let us serve you.Contact us