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Technical Note (National Research Council of Canada. Division of Building Research), 1962-01-01
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Vibration observations and recommendations regarding the installation
of an electron microscope
Crawford, R.
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r
NATIONAL RESEARCH COUNCIL OF CANADA
NOT FOR PUBLICATION
355
No.
FOR INTERNAL USE
CHECKED BY T. D. N.
DIVISION OF BUILDING RESEARCH
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CAlL
PREPARED BY R. Crawford
••••
ｾ January 1962
PREPARED FOR
D. H. Laughland, Research Branch, Canada Department of Agriculture
SUBJECT VIBRATION OBSERVATIONS AND RECOMMENDATIONS REGARDING
THE INSTALLATION OF AN ELECTRON MICROSCOPE
The object of this study was to measure background vibration levels at the proposed sites for a new electron microscope in rooms B65 and B54 in the K. W. Neatby Building, Central Experimental Farm, Ottawa. The level of vibration of the present microscope installed at the Plant Research Institute was measured under normal operating conditions.
Vibration pickups sensitive to particle velocity were used in con-junction with associated electronics to measure the vibration levels. The present set-up in the Plant Research Institute, was reported to be satisfactory and accordingly the vibration levels are taken as a standard for comparison pu.rposes. It is, of course, conceivable that somewhat higher levels would
still be tolerable. The observations and locations of the pickups are shown in Table I and Fig. 1, respectively.
Room B65
Room B65 is composed of three ｳｾ｣ｴｩｯｮｳＬ A, Band C. Section A contains a cold room, and two compressors are tied down to the main floor (Fig. 1). Section B is a small room used as a glassware store; Section C is a general purpose storeroom next to the main corridor. Adjacent to sections A and B there is a workshop where a number of grinders are in frequent operation.
Generally there appear to be three separate vibration sources
applicable to Room B65: the grinders next door, the cold room compressors and extraneous noises from the corridor and elsewhere. Considering the
.
.
2
-of 1.5X the standard. The addition of the grinders causes a jump to 3. 5X. In section B, the glassware store, the effect of the compressors is not notice-able but switching on the grinders brings the level up to lOX the reference level. The storeroom adjoining these two rooms, section C, is much quieter being the same as the standard when both the grinders and compressors are on. Owing to the proximity of the corridor and the elevator shaft, however, fluctuations of up to 4X were observed when a hand truck was pushed along the corridor. Opening and closing of the elevator door caused smaller fluctuations and generally fluctuations occurred when there was activity in the corridor. Room B54
This room is very quiet at the end remote from the door where the level is about O. 3X the standard. Fluctuations from this were barely detectable when doors were slammed and compressors across the passage were turned on.
Conclusions
It is seen that Room B54 at the end remote from the door is the quietest situation for the electron microscope. If, however, a situation noisier by a factor of 1. 5X, with occasional higher fluctuations, say 4X, can be tolerated then it is possible that the end of section C, again remote from the door, would be feasible.
3
-TABLE I - VIBRATION MEASUREMENTS Location
Plant Re search Institute
Component Peak Amplitude in.
Is
e c x 1 0 - 3 Remarks 3 ft from door 3 ft from door In corner behind microscope In corner behind microscope K. W. Neatby Building Room B65 V 1. 46 Electron microscope running normally H 0.57"
V 0.42 II H 0.10"
Main room A Main room A Main room A Main room A Glassware store B Glassware store B Glassware store BStoreroom C at the end remote from door
"
"
Room B54 Room B54 V 0.26 V 2.24 H 0.78 H 4.96 V 0.26 V 3.38 H' 13.80 V 0026 V 1. 20 H 1. 41 V 1. 82 H 1. 20 V 4.50 V 0.52 H 0.26Cold room compressors off Cold room compressors on Cold room compressors on Cold room compressors and grinders next door on
Grinders off, compressors on
Grinders on, compressors on
Grinders on, compressors on
Grinders off, compressors on
Grinders on, compressors on
Grinders on, compressors on
Elevator door slammed, lab doors closed
Elevator door slamnled, lab door s closed
Heavy hand truck passing in corridor
End remote from door End remote from door Slamming doors etc. made no difference
