Guards need to be installed in cases where the designer has failed to achieve intrinsic safety through avoiding trapping and similar dangers. The consideration for choosing guard materials are strength, stiffness, durability (to cope with both continuing and contingent dangers) and the possible effects of the guard material on machine reliability. A solid guard may create problems of cooling and visibility.
There are both operational and safety reasons for a clear view of the danger area. An important factor in non-solid or mesh guard material is the size of the opening in relation to its distance from the dangerous part.
A fixed guard is a guard with no moving parts. When fitted, it should be incapable of being displaced casually, so the method fixing is very important. These guards should be affixed in such a way that they can only be opened with the aid of a tool. Guard removal time should be kept to a minimum.
A distance guard is simply a barrier situated at an appropriate distance from the barrier. The degree of risk being faced will determine whether a fixed rail or fence is needed.
The following question should be answered when assessing machinery safety:
- Does the safeguard totally prevent approach to dangerous parts?
- Is the safeguard reasonably convenient to use?
- Can the guard be defeated or is it susceptible to misuse?
- Are the instructions for safe use of the machine and safeguard adequate to cope with all foreseeable dangers in use?