Bulletin 162 Complete

The page numbers refer to the pages in the pdf. (The numbers in brackets are those given in the actual bulletin)

3(1) Announcement

Changes to SSSERC service

4(2) COSHH Regulations

By now many teachers and technicians may be vaguely aware of the “Control of Substances Hazardous to Health Regulations” — ‘COSHH’ for short. These regulations have already been laid before Parliament and will take effect as from October of this year with further requirements as from January 1990.

7(5) Gas taps, a reminder

We again would draw your attention to the need for inspection of anti—rotation provision on laboratory gas taps and for prompt remedial action where that is found to be necessary.

7(5) Vacuum flask implosion

We have received an account from a school of such an implosion during a calorimetry experiment.

7(5) Explosion in a flask

A round- bottomed flask fitted with electrodes and used for the sparking of air to show the combination of nitrogen and oxygen in air. It was wshed with ethanol to speed drying . . .

8(6) Implosion, carbon filament lamp

Another bang with broken and flying glass. It is of particular interest because it highlights differences between carbon filament lamps, used for certain physics activities, and lamps of the more usual tungsten filament type.

9(7) More on lamps, ES fittings

We have had, very recently, notice of an accident involving a sodium lamp with an Edison Screw fitting.

10(8) Pupils wiring plugs

Risks from a common method of carrying out this activity.

10(8) Permitted access to mains

Control of pupil-wired devices.

11(9) Measuring mains voltage An improved method

12(10) Thermistors:

Simple means of getting accurate temperature data. this technique is explained and illustrated. A computer listing is given to take out some of the mathematical sweat.

15(13) Biotechnology: microbial fuel cell

We have been trying out such a  cell based on ordinary baker’s or brewer’s yeast Saccharomyces cerevisae. We have been much impressed both by the performance of this device and the principles behind it.

17(15) Electronic thermometers tested

There are now dozens of models of cheap digital thermometers on the market. How good are they?

22(20) Surplus equipment offer

Bulletin 163 Complete

3(1) Opinion

4(2) Introduction

Waffle waffle, Bulletin distribution, Change of address and phone number, Staff: ‘old’ and ‘new’, —Saturday opening, Technological Studies

7(5) Soldering — what precautions to take

We have been asked to give advice on what precautions to take in soldering. The advice which follows is pertinent to both staff and pupils.

9(7) Bursting bottle experiment

The risk that can be encountered, through not following safety instructions, when using a Bursting Bottle.

9(7) Iodine filter for infrared

Use of an iodine solution to filter out visible light but allow IR through.

10(8) SSERC and Technological Studies

We hope that we at SSERC can assist technology teachers by offering advice and, through a series of articles in subsequent bulletins, provide useful technical support and some relevant resources.

22(20) Reflex action

A method for estimating the latency period of a reflex action is described. Hints on the construction of a hammer with a built-in triggering mechanism are given.

27(25) Gas volume determination – another method

Another method for gas volume determination has been suggested by Sid Gallagher of Campbeltown Grammar. This method still allows access to interfacing packages but without the requirement for a precision glass syringe.

29(27) Buffer solutions – a market survey

The costs of chemicals used in DIY preparations of buffers are compared with those of  commercially available buffer solutions, sachets and tablets.

29(27) Buffer solutions – DIY preparation

The details for a number of buffer solutions are described.

32(30) DIY transducers for distance and velocity v. time

Designs are outlined for two novel, cheap and easily constructed transducers with voltage outputs directly proportional to (1) distance and (2) velocity. Several applications are described.

37(35) An op-amp tachometer

The back e.m.f. of a motor is directly proportional to its angular speed. In this method the back e.m.f. is derived algebraically by subtracting the voltage dropped across a series resistor from the voltage developed across the motor. The output signal is thereby a function of speed.

39(37) Evaluation report — the Motion Sensor

An ultrasonic rangefinder linked to a BBC Computer through the computer’s User Port.

41(39) After the Master – which computer?

The Master is of course still available. Why are we considering ‘the next’ machine at all? The new generation of machines give you more computing power for your money; but do you need more computing power?

43(41) Trade news

44(42) Surplus Equipment Offers

Bulletin 164 Complete

The page numbers refer to the pages in the pdf. (The numbers in brackets are those given in the actual bulletin)

3(1) Opinion

COSHH’ed to death

4(2) Introduction

Christmas closure, Standard Grade costings, SSERC publications for Standard Grade, MISAC advisers, no comment

6(4) Portable socket outlets

We draw your attention to a portable socket outlet having a design feature that is hazardous and places the user at risk.

6(4) Flexible cords

Flexible cords – often called flexes – are the cables that connect portable electrical appliances to socket outlets. We describe here two special types of flexible cord that you may need to use.

7(5) Philips spectral lamps – polarity checks

We recently issued a circular advising authorities to carry out several checks including one on the polarity of wiring to the Edison screw lamp fitting. Unfortunately we did not explain how such a check should be done.

9(7) Eye protection

Our article in Bulletin 163 on the precautions to take when soldering included stating the requirement that eye protection must be worn. We would like expand on this to make explicit what is required. This comment pertains to any such hazardous activity, not just soldering.

9(7) Microwave apparatus – HT hazard

Hazards associated with some older models of microwave.

9(7) Harris protactinium generator

We understand that a number of bottles containing this radioactive source have leaked.

10(8) COSHH in schools

The Health and Safety Commission  (Education Service Advisory Committee) has published its very readable booklet “COSHH: Guidance for schools”. A summary.

18(16) Standard Grade costings – S.G.Technological Studies

Our estimates for equipping Technological Studies.

29(27) Power supplies for electronics and technology courses

The choice of suitable power supply types for electronics and technology courses is discussed and proper usage described. The article should be  of interest to anyone using electronic circuitryfor instrumentation and control.

37(35) Soldering stations tested

We review various models.

40(38) Pulse monitor update

This area of the market has remained dynamic and the intention here is simply to give a summary of the results of more recent evaluation work since our last article.

44(42) Electronic thermometers – more models tested

We report on seven models of digital thermometer. This supplements the eighteen summarized in Bulletin 162.

46(44) Surplus Equipment Offers

50(48) Notices

The Biochemical Society, British Society for History of Science, ‘Biotechnology Education’