Guard interlocking


An employee severed his arm in a rotary valve to which access had been gained through a hatch. He had been trying to clear a blockage. The crop had blocked the cyclone causing the line to shut down. He opened the access door in cyclone to clear wet product, which wasn't dropping correctly onto conveyor. Instructed by the shift supervisor he then opened another lower inspection hatch. He was somehow grabbed by the conveyor. As he tried to put his arm out to grab the edge of hatch, he missed and his arm went into valve. As a result his arm was severed below the elbow including two fingers across top of hand - arm put back on and two fingers plus thumb.


There was no safe system of work in place for clearing blockages in the cyclone, and the method adopted had been routinely used to deal with the problem prior to the accident.

The unmarked switch for the rotary valve, coupled with lack of training, significantly contributed to this accident. This accident was entirely foreseeable and simple, appropriate controls had not been implemented. As a result, the company was prosecuted under:

  1. Section 2(1) of the Health & Safety at Work etc. Act 1974 for not having a safe system of work in place coupled and failure to provide training in a safe system of work for unblocking the cyclone; and
  2. Regulation5(1) of the Provision of Workplace Equipment Regs 1998 (PUWER) for failing to mark the switch on the rotary valve.

Noting that this was the third time the company had appeared in court for failing to prevent access to dangerous parts, the judge took particular note of the "appalling" injury suffered and imposed a fine of £32,500 together with the prosecution costs of £11,000.


Covers which are required to be removed frequently for any purpose should be inter-locked. Standard of interlocking required is to be determined by a risk assessment. If the machine has to cool down after heaters are switched off, time delay interlocks should be fitted to covers giving access to dangerous parts. The machine should be provided with means of isolation which complies with the machinery directive and which are clearly labelled. Multiple means of isolation may be required. Control circuit switches are not "isolators" - a safe system of work is required.