Load sensors and vibration transducers Graham & White Instruments are now agents for a range of equipment manufactured by the Helm Instrument Co of Ohio, USA. These are chiefly non- contact vibration and displacement display and alarm systems but also include a bolt-on strain sensor for monitoring loads in large machines. They also offer control equipment from other American manufacturers. Details from: Graham & White Instruments, 82 London Road, St Albans, Herts. Tel. St Albans 59373 and 61 110.

Constant current supply and common dummy for strain measurements Intercole Ltd now have two new features in their Compulog System to minimise installation and material costs in strain tests. Constant current supply in the Commutating unit minimises the effect of lead resist- ance and the common dummy facility enables a saving in appropriate tests. There are no price increases. Details ,from: Intercole Systems Ltd, Chandlers Ford Industrial Estate, Eastleigh, Hampshire SO5 3 YU. Tel. Chandlers Ford 4 72 7.

Strain gauge amplifiers Two new high-performance strain gauge amplifiers have been introduced by Strainstall Ltd. The 605A gives full scale output for 30 microstrain single active gauge and the 91C gives full scale output of 0.1 mV/V for transducer use. Both operate from 12 volts unstabilised supplies.

Strain gauge switch unit This manual switch, from Stainstall Ltd., enables selection of twenty-four half or full-bridge circuits or seventy-two quarter-bridge circuits which is most useful with three-gauge rosettes. True zero reference and calibration facilities are included.

Checkpoint magazine Strainstall Ltd are issuing an eight-page periodical magazine under the title Checkpoint giving some idea of the industrial and engineering projects in which they are involved. Details from: Strainstall Ltd, Harelco House, Denmark Road, Cowes, Isle of Wight. Tel. 098-382 2219 or 2360.

summaries Do we measure strain when we measure strain 7 C. Peekel Strain, Vol. 8, No. 3, July 1972, p . 112 Errors can occur in the measurements from a strain gauge installation unless certain precautions are taken. Practical solutions are given to minimise the influence of temperature, moisture, etc. to ensure an acceptable zero stability.

Press load monitor H. Coulson Strain, Vol. 8, No. 2, April 1972, p . 107

The article describes the design and use of an instrument which displays the peak frame load during a single operating stroke of a press. It consists of a strain gauge link permanently bolted to the frame of each press to which a portable electronic unit is connected. The technique of using a strain gauge link eliminates the problems encountered when a load cell is used, or when a strain gauge system is bonded directly to the machine frame.

The use of photoelastic strain gauges i n i nd ust r ial transducers G. R. Higson Strain, Vol. 8, No. 3, July 1972, p . 122 Two types of transducer, using photoelastic strain gauges, developed for use in mines are described. It is believed that robust self-contained transducers of this kind could find wide application in other industries where high accuracies are not necessary.

Application of a digital computer in the processing and presentation of tensile test results D. Fitzgeorge and A. R. Rowlands Strain, Vol. 8 , No. 3 , July 1972, p . 117 A computer program has been prepared to receive the longi- tudinal and lateral strain readings taken during tensile tests on cast irons and to compute from them the longitudinal and lateral moduli of elasticity and Poisson’s ratio. The results are presented as mathematical functions of stress.

Instrumentation techniques for strain measurements in concrete pressure vessels and similar structures 1. W. Hornby Strain, Vol. 8, No. 3, July 1972, p . I10 This paper describes instruments and techniques that have been employed by the Central Electricity Generating Board for short and long term strain measurements in prestressed concrete pressure vessels, and the methods adopted for data logging and subsequent data reduction. The measurements and tests on samples required to interpret the site readings are also described.

146 ‘Strtzin’, July 1972

PHI LI PS

Moments of stress -precisely! Ptrilips can offer electro-analogous transducers and measuring equipment for the determination of a variety of ni cc t 1 an i ca I para meters. T t i ese comb in at i o n s a re co in p a r t , r d i a t i l e and extremely accurate ~ they cover strain, I J r 3 5 s u re, d is p I a c e ni e n t , tor (1 u e, v i brat ion and t e ni p e rn t I I re ineasutement w i th far greater simplicity and flexibility th,in niechanical methods. And u I cc t ro - an a I og o u s I y determined meas u reni en ts ti i ive ottie: major advantages. For example, they are naturally ( oinpatible w i th data-processing systems and provide for rapid analysis of complex test set-ups. As Phil ips transducers are no t limited by position they can be apptied at any angle the application calls for They ;ire a lso protected against most adverse environnient,il (:o 11 d I t I on s Ask Pye Unicam n o w for full information o n the Philips r,inge of transducers and associated instruments t h a t c:ould put a new stress o n precision in many of your mechanical me ti :, u r i ng pro b I ems.

& *

PYE UNICAM LTD p*

I SHORT RANGE TELEMETRY EQUIPMENT FOR USE WITH STRAIN GAUGES AND THERMO- COUPLES SIMPLE TO USE * PROMPT DELIVERY - COMPLETE SYSTEMS FROM f420

INTERNATIONAL ENOINEERINO CONCE8SlONAlRES LTD for further details contact

WELLINGTON HOUSE, WALTON-ON-THAMES, SURREY. TEL: WALTON-ON-THAMES 2221 1 TELEX 21 201

Could you use a 5ton load cell- priced at €35?

STRAINSTALL LIMITED Harelco House, Denmark Road, Cowes, Isle of Wight, England Telephone Cowes (098-382) 221 9/2360 Telex 86369

5El

STRAINSTALL can provide: COMPRESSIVE CELLS from 1 Kg.f. to 1,000 T0n.f. TENSILE CELLS from 1 Kg.f. to 100 Tond. ANALOGUE READOUT 1 from f70! OR DIGITAL, 3% DIGIT ? from fl50!

from f340! OR WITH PRINTER ?

We have a vast range of transducers and instrumentation which has been designed to high engineering standards but which is available to you a t low prices. We have load cells which will operate in sea water to depths exceeding 200 ft. We have multi-element load cells which measure up to 600 tons deep underground, and will keep on working. We have special load cells which do not mind side loads or shocking misalignment. If you have a weighty problem, we probably have the answer. Why not write, phone or Telex? With the range that we have available, there i s a good chance that we have the load cell and the instrumentation in stock for prompt delivery.

148 'Strain', July 1972