Document MJ02byvjYqrjKyo03oNMaD42j
3S K. L. Knicht and D. E. Hickish
Vacuum brush The vacuum brush shown in Fig. 2 consisted of a circular nylon bristle brush
mounted on an angled handle and fitted via the handle to the same vacuum cleaner. In use, the brush was used to remove dust from drums and assemblies under vacuum.
EXPERIMENTAL PROCEDURE
In order to determine which of these two methods was the better, the performance of each was compared with the traditional blow-off method, in two separate experi ments shown in Table 1.
Table. 1. Effect of cleaning methods on dust concentrations
Hour Activity
1 Back ground
2 Blow-off
5 Back
ground
66 Funnel Brush cleaning cleaning
Personal sampler Static sampler Peak sample
particles/cm* fibres/cm* particles/cm* fibres/cm* particles/cm*
fibres/cm*
Personal sampler Static sampler Peak sample
particles/cm* fibres/cm*
particles/cm*
flbres/cm' particles/cm*
fibres/cm'
116 0-96 161 0-45 '
422 5-35 72 0-52 41750
87
107 0-9S 162 0-41
415 3-5 210 0-75 759 1-04
125 635 016 0-84 129 155 0-10 0-16
41750
87
140 0-09 110 0-20
158 0-22 122
0-18 310
0-57
During the first hour of the day air samples were collected to determine background concentrations; during this period the near side front road wheel was removed. In the second hour samples were collected during dust removal from the near side brake assembly by blow-off. Further background samples were taken during the fifth hour while the off side front road wheel was removed, and during the sixth hour dust determinations were made while either the funnel or the brush cleaning methods were used.
The personal samples were collected from the breathing zones of mechanics en gaged in the work and static samples were collected concurrently to simulate exposure of mechanics working in an adjacent repair bay. Short duration samples were also collected by means of a Drager pump from the operator's breathing zone at the peak period of dust generation.
All the samples were subsequently analysed for fibres in accordance with the technique laid down in the Hygiene Standardfor Chrysolite Asbestos published by the British Occupational Hygiene Society (1968). Particle counts were limited to particles greater than 1 p. dia.