User Manual

SAFETY
Safety handbook page - 24 -
PNSPO
6.0 Two hand controlling
To protect workers that are directly exposed to dangerous areas and need to access a
hazardous zone, the usage of Two-hand control devices is an appropriate solution.
Compared to a safety door that builds a barrier between user and hazard, the Two-
hand control forces the operator to keep both hands on the control actuating device
while the machine is executing a potentially dangerous movement.
Definition, EN 574 (1996) 3.1:
“A device that requires at least simultaneous actuation by the use of both hands in
order to initiate and to maintain, whilst a hazardous condition exists, any operation of a
machine thus affording a measure of protection only for the person who actuates it”
The use of Two-hand control devices is common in machinery for example, hydraulic
presses (EN 692) , mechanical presses (EN692) and pneumatic presses (prEN 13736).
A Two-Hand control device has to be designed carefully, taking account of EN 574
specifications. The main concern is to prevent any possible means of defeating the
built in safety function.
6.1 EN574 and EN999, relevant standards
6.1.1 EN 574, Basic Requirements for Two hand control devices
The EN 574 specifies the requirements for Two-Hand control devices.
The norm defines “Types” of devices and explains the requirements in Table 6.1.
Type III
Requirements according EN 574
Type
I
Type
II
A B C
Use of both hands (simultaneous actuation) X X X X X
Relationship between input signals and output signals X X X X X
Cessation of the output signal X X X X X
Prevention of accidental operation X X X X X
Prevention of defeat X X X X X
Reinitialisation of the output signal
(after the release of both control actuating devices)
X X X X
Synchronous actuation (within 0,5 s) X X X
Use of Category 1 (EN 954-1) X X
Use of Category 3 (EN 954-1) X X
Use of Category 4 (EN 954-1) X
Table 6. 1 List of types of two-hand control devices and minimum safety requirements