Eyepiece Reticles from Graticules Ltd.

Asbestos fiber analysis

Walton and Beckett Reticle for Asbestos
Calibration factors are required for each of these three reticles (see important note below).

The Walton and Beckett reticle is used for counting fibrous dust (e.g. asbestos or glass fibers) and is particularly useful where the majority of fibers to be counted are shorter than 5 痠. The circle is divided into four by two diametrical lines scaled in units of 5 and 3 痠 respectively. It turns out that 3 and 5 痠 are the critical measurements of fiber lengths and diameter used in fiber counting. Unlike the usual globes of other particle reticles, the Walton and Beckett has a series of shapes to which analyzed features can be compared. The shapes have been carefully designed for direct comparison with fibers, especially since they incorporate an aspect ratio of 3:1 or 5:1, essentially for such analysis.

Reference: W. H. Walton and S. T. Beckett, Occupational Hygiene Vol 20, 19-23, "A Microscope Eyepiece For the Evaluation of Fibrous Dusts."

Important note before placing an order:
The circle on these Walton and Beckett reticles must represent 100 痠 at the stage and each one must be custom manufactured to suit each individual instrument. Therefore, in order to properly manufacture the appropriate reticle, you must provide SPI Supplies with the following information with your order:

Calibration factor or the information for us to calculate it for you which would include:

Objective magnification
Eye piece magnification
Diameter of reticle disc required
Microscope make and model

When placing an order via the Shopping Cart, place the order first, getting the order Reference Number, then send us an e-mail making sure you reference the order Reference Number and then give us the needed information.

Walton and Beckett for asbestos counting, 3:1 aspect ratio. Glass sandwich
Pattern G22	SPI #	Each	In Stock	Click Images for Larger View
16 mm	GR01A16062-AB	$ 305.72	No
19 mm	GR01A19062-AB	305.72	No
21 mm	GR01A21062-AB	305.72	Yes
27 mm	GR01A27062-AB	324.74	No

Walton and Beckett for asbestos counting, 5:1 aspect ratio. Glass sandwich
Pattern G24	SPI #	Each
16 mm	GR01A16063-AB	$ 305.72	No
19 mm	GR01A19063-AB	305.72	No
21 mm	GR01A21063-AB	305.72	No

Walton and Beckett for asbestos counting, 5:1 aspect ratio; glass sandwich. This pattern is based on a new design by the Institute of Occupational Health, United Kingdom.
Pattern G25	SPI #	Each
16 mm	GR01A16085-AB	$ 305.72	No
19 mm	GR01A19085-AB	305.72	No
21 mm	GR01A21085-AB	305.72	No

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