a Guidance for Safe Use of Kilns in Occupational by zaaaaa4


DATE: 7 MARCH 2000                                       DOCUMENT NO. H&S 0044
ISSUE NO: 2                                              PAGE 1 OF 2

         Guidance for Safe Use of Kilns in Occupational Therapy Units

1) Introduction

Many occupational therapy units use pottery as an essential part of the therapy process. These
workshops are served by small electrical lift cover kilns which are operated on an occasional rather
than continual basis. Provided basic guidelines are followed, their use is perfectly safe. However if
these guidelines are not followed there are a number of potential hazards that may injure staff and

2) Protection from hot surfaces

Kilns, during the firing process, can reach internal temperatures of between 500oC to 1200oC which
results in the exterior of the kiln exceeding 100oC despite insulation. This is quite sufficient to cause
burns to anyone who may come into contact with the kiln.

Kilns should therefore be either sited in a locked room where they cannot be accessed by clients and
untrained staff or, where this is not possible, provided with a cage surrounding the kiln to prevent
inadvertent contact. Cages must be provided with padlocks to secure them when the kiln is in use and
allow full visibility of the kiln so that no one can be accidentally locked inside.

Kilns should be fitted with a temperature indicating device so that operators can ensure that the kiln is
sufficiently cool to unload fired pottery.

All kilns should be marked with appropriate hazard warning signs, that is a black triangle on a yellow
background indicating a thermal hazard.

3) Electrical safety

Internal heating elements on many kilns contain un-insulated conductors running across ceramic
supports. These elements are live when the kiln is operating. It is therefore essential that an interlock
is fitted to the lid of the kiln to isolate power should the lid be opened. Best practice is to ensure the
kiln is isolated and locked off prior to any inspection of the contents or loading and unloading
operations. The interlock should not be the sole means of ensuring the power is off. Locking off the
isolator also prevents unauthorised use of the equipment

Kiln installations should be subject to regular inspection and testing under maintenance schedules.

4) Fire prevention

The high operating temperatures and radiant heat of kilns obviously pose a fire hazard. All
combustible materials such as paper, cloth, wood, solvents paints and glues etc should be kept well
away from the kiln. Nothing of a combustible nature should ever be placed inside the kiln.

5) Insulation – hazards during maintenance and use

Kilns are lined with fire resistant materials to withstand the high temperatures. These materials may
include ceramic fibre, fire brick or asbestos (in the case of old kilns). Any asbestos must be identified
and labelled to warn operators and maintenance staff. Asbestos and any other insulation materials
must never be tampered with or repaired by any O/T staff. Ceramic fibres or man made mineral fibres
(MMMF) are also hazardous to health and should not be cut, drilled or otherwise damaged or handled.
 Work on all fibrous materials requires assessment of risk, dust control, respiratory protection and in
DATE: 7 MARCH 2000                                      DOCUMENT NO. H&S 0044
ISSUE NO: 2                                             PAGE 2 OF 2

certain circumstances a special licence. Any damage to these materials must be reported immediately
and the kiln taken out of use.

Materials in good condition can be used safely provided they are treated with care and not abraded or
physically damaged during use. A regular inspection and assessment is however required.

6) Safe Working Procedures

All kilns must display the manufacturers instructions for:

1   Start up procedures
2   Operating procedures
3   Shut down procedures
4   Emergency procedures

Where operating instructions were not provided, these must be drawn up with the manufacturers
consultation. Operators of kilns should be trained in these operating procedures. Kilns should not be
operated by clients.

When the kiln is operating warning of this should be visible by use of an indicator light. A log of the
start and finish times of firing should also be maintained as this will aid communication with other staff.

7) Risk Assessment & substitution of hazardous substances

Glazes and paints should be assessed for risk. Data sheets should be examined for hazardous
components and where there is scope to reduce toxicity through substitution to less hazardous
materials (i.e. lead free or leadless compounds) then this should be done. Skin contact or ingestion
during application of slip, paint or glaze may be the most significant route of entry during the whole
process. Substitution is the preferred option over ventilation and other controls.

Some glazes and clays may give off fumes during firing which can be hazardous to health. The
exposure will depend upon the glazes and paints used and the source of the clay. An assessment will
indicate whether ventilation is required or not. However it must be borne in mind that ventilation also
serves to remove some of the heat generated by the kiln.

In most applications the frequency of firing is low and exposure will be correspondingly low. If
ventilation is required on it may be either by general ventilation if the kiln is sited in its own purpose
built room or by means of a hood and ductwork where the kiln is placed in a workshop inside a cage.
Ventilation should operate as soon as the kiln is switched on to prevent a build up of fumes and heat.
Ventilation is subject to the test requirements under the Control of Substances Hazardous to Health
Regulations (COSHH) where inspection should be undertaken every 14 months.

8) Housekeeping

Clays should not be allowed to dry out, particularly on work surfaces and floors. Dried clay can result
in fine dust that can be breathed in. Clay dust is hazardous to health as it contains silica. Dried
deposits should be wet mopped. Dry sweeping may generate a cloud of fine dust particles.

9) Review

This policy will be reviewed by 7th March 2001.

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