Intrinsically Safe Digital Indicators

MTL630 Series
3 1/2- and 4 1/2-digit Intrinsically Safe Digital Indicators

Display process variables in hazardous areas Install directly in hazardous areas Built-in references for easy calibration Large liquid crystal displays IP65 enclosure - suitable for field or panel mounting Non-energy-storing apparatus MTL633B 31/2 - digit display 4/20mA loop-powered less than 1V drop under all conditions MTL636 41/2 - digit display mV or mA input capability ratiometric mode for load cells MTL637 41/2 - digit display temperature indicator direct thermocouple or RTD input alarm trip facility

The MTL630 Series Intrinsically Safe Digital Indicators enable process variables to be displayed locally in even the most hazardous plant areas. Each unit is housed in a moulded polycarbonate case which is dust-tight and hoseproof to IP65 to allow for installation in the field or on a control panel.

Large liquid crystal displays make the process values easily visible at a distance and a slot-in label after the last digit allows the unit of measurement to be shown, together with the loop identification if required. A set of labels is supplied, pre-printed with a selection of legends or, alternatively, one of two blanks also supplied can be user-labelled as required.

The MTL633B is a loop-powered 4/20mA indicator needing less than 1V. The unit is provided with linear or square-root extraction options. The latter is set by a link and indicates directly the flow from a differential pressure measurement loop using an orifice plate, Dall tube, venturi, etc. This mode is precise, being based on a pulse-width/pulse-height squaring circuit in a feedback loop.

The MTL636 is designed primarily for load-cell and other bridge-circuit applications for which it can be used, if required, in 'ratiometric' mode (displaying the mV signal divided by the bridge supply voltage) to eliminate possible errors caused by supply voltage variations; but it can also be used for absolute measurement at ±0 to 100mV or
4/20mA signals, either separately powered or loop powered.

The MTL637 is specifically designed for temperature applications, accepting signals from thermocouples (or other mV sources) and RTDs.

Certified as 'non-energy-storing' simple apparatus ('non-voltage-producing' in the USA), MTL630 Series indicators can be inserted directly into any IS loop without further certification.

All models can be mounted on posts or pipes, on flat surfaces, or on control-room panels in any zone.

Data Sheet