Valve Actuation

Field Barrier – Type 3770


The field barrier is suitable for operating positioners, smart positioners using HART protocol, i/p converters, solenoid valves or limit switches.

Upstream connection and direct attachment to intrinsically safe field devices enables the intrinsically safe circuits of these devices to be connected with the circuits of upstream input and output units that are not intrinsically safe. So the advantages of intrinsic safety such as putting into operation and working when connected to a voltage source are still in effect within the hazardous area.

The connecting cable of the not intrinsically safe circuit is introduced in the housing of the field barrier either via pipeline systems or via design-certified metal cables and wire entries.

The field barrier transmits the analog reference variable to i/p converters and positioners. The use of HART protocol is also possible. The version with three channels additionally allows the connection of either two limit switches according to DIN 19 234 or two intrinsically safe solenoid valves.

When using an adapter M 20 x 1.5, the field devices can be connected to one another via direct cable entries.


Field barrier with flameproof enclosure serving as interface between intrinsically safe and not intrinsically safe circuits in hazardous areas.

Principle of operation

Channel 1 of the field barrier is especially designed for transmitting analog signals in the range of 4 to 20 mA, but it also transmits the HART protocol.

The optional channels 2 and 3 are intended for controlling limit switches according to DIN 19 234 or Ex i solenoid valves. They may be used, for example, for the fail-safe venting function in the Types 3780 or 3767 Positioners with a solenoid valve using 6 V.


The field barrier possesses a connecting adapter with male thread M 20 x 1.5, allowing direct mounting on an intrinsically safe field device, such as Type 3780 Positioner. If the wiring method is used, the cable ends must be connected to a Ex i distributor box. The input is provided with a 1/2? female thread connection.