FILTER CUT POINT DETERMINATION
- a new high precision method

  Unique super-sonic method of calibrating filters
Wide calibration range - from 5 to 1000mm
Filter cut points traceable to NIST & NPL
Glass microspheres give unambiguous results
Accurate to 1mm for the smaller filter apertures
Maximum pore size can easily be verified
 

A Novel Sonic Sifting Approach
20 narrow distribution microsphere standards have been produced and certified by Electroformed sieve analysis and microscopy using a NIST reference. A single-shot vial of the appropriate standard is first fluidized on the filter by a computer controlled Sonic sifting device.

A Calibration graph supplied with each standard is then used to relate the percentage passing to the filter cut point. Because the particle size distributions are so narrow, a 10% weight difference passing a filter only equates to a 2mm change in pore size. The graphs below show the construction and use of the filter calibration graphs.

Certifying the Standards
Each of the filter calibration standards have been analysed 5 times using Electroformed sieves traceable to NIST and NPL. To give confidence in interpolation, the data is supported by microscopy.

Application
This unique method of filter calibration may be used on all forms of complex woven and non-woven materials that are impossible to calibrate by other means.
  
  

 
Note:
The efficiency of the sonic sifting device is dependent on the thickness of the filter to be analysed. Although the instrument is capable of analysing down to 5mm, for sizes below 25mm, an ultrasonic suspension method employing ultrasonics may have to be used.

Analysis of the microspheres passing can be used to determine the maximum pore sizes in the filter.

Requirements
Preferred size of filter media for testing = 90mm diameter discs
2 discs are required per test, one for test determination and set up and a second for the official test.
  

Turnaround time < 1week

 
Prices
 

Pore Sizes (mm)
1000 - 25  25 - 5
Sonic Challenge (dry) Ultrasonic (wet)
£
 GBP		 €
 EURO*		 $
 USD*		 £
 GBP		 €
 EURO*		 $
 USD*
150 230 300 200 305 405
The following discounted price is available for sending 10+ samples in a single order
115 160 225 175 265 345

  * Currency conversions are provided as a guide only and are therefore subject to slight fluctuation

 

PORE SIZE DISTRIBUTION ANALYSIS
Procedure

Sand screens are Challenge Tested using the sonic method to provide a cut point.  From the cut point a projected maximum pore size can be calculated.  This has been shown to be approximately 10% above the cut point.

To measure Pore Size Distributions, the mesh from the challenge test is inverted and gently tapped to remove oversize calibration microspheres.  The mesh is then returned to the sonic sifter in the inverted position to remove the ‘near mesh’ microspheres trapped in the body of the sand screen.  The near mesh particles are collected and analysed by microscopy and image analysis.  The sizes at 3%, 50% and 97% of the cumulative distribution are noted and ascribed to the minimum pore size (P3), Average pore size (P50) and Maximum pore size (P97) respectively.  The absolute minimum and maximum bead sizes reflect the single smallest and largest pore detected but the results are not as statistically robust as the P3 and P97 values and therefore not as reliable.

Notes: The maximum pore sizes obtained from the cut point and from the ‘near mesh’ analysis should be within 10%.  If P97 is more than 10% above the projected maximum, there are likely to be larger internal pores that do not penetrate the structure.
 
Prices
 
Cut Point price plus an additional
£200     € 305*     $ 405*

 

  * Currency conversions are provided as a guide only and are therefore subject to slight fluctuation