Some incidental safety device (indirect guards) equally useful as machine guarding are as below:-
Two hand control:- Two push buttons are required to be operated simultaneously thus keeping the operators hands engaged and away from the dangerous part. Such device does not protect another approaching person is prone to faults and cause difficulties on electrically, hydraulically or pneumatically powered machines. Therefore such device alone is not advisable. It is used on garment presses etc. Where two operators have to work simultaneously four push buttons are required to keep their hands away from dangerous parts.
Optical Sensor:- This uses photo-electric cell and a light on interruption of light beam, the dangerous part is stopped. Its working must be checked before starting the work.
Electromagnetic Sensor:- This uses a sensor of electromagnetic field, a coupler and interconnecting cable and a control unit. Interruption of the field by an operators hand cause an electric signal which initiates the desired control action.
Mechanical Feed:- A positioning device like conveyor or a rotating table moves the parts or material in to the point of operation where the hazard exist thus avoiding human contact there.
Feed Tools:- Tools tong, magnetic, lifting rod etc. are used to place material in a press with an intention to save the hand.
Pedal Guard:- Such guard on foot-pedal of a power press prevents accident foot-stroke on the pedal.
Ultrasonic device:- Inaudible high frequency sound senses the presence of any part in the danger zone. As sound attenuates over distance its application is limited.
Feed hooper : It extend the feed length to prevent access. It can be used on pug mill, rubber mill etc.