Melt pressure sensor (transmitter)

is a precise measuring device that uses high-performance core components and an integrated analog-to-digital circuit design. Through program-based linear compensation, it achieves high measurement accuracy. Only with proper handling can its service life be extended. Care must be taken when installing the sensor (transmitter). The following are some precautions for installing and using high-temperature melt pressure sensors (transmitters), including proper connection and debugging, to ensure trouble-free operation.

01 Installation Method

Installation

When installing the pressure sensor (transmitter), it is essential to ensure that the sensor (transmitter) hole is within the dimensional requirements specified in the drawings below. Assembly accuracy can be verified using a test bolt. Figure “a” shows the correct installation position, while Figures ‘b’ and “c” show incorrect installation positions. Before installing the sensor (transmitter), first clean any debris from the hole and between the thread teeth. Then apply thread anti-seize grease to the sensor (transmitter) threads, as the external and internal threads of stainless steel are prone to thread seizure. Applying thread anti-seize oil prevents thread seizure. When installing the sensor (transmitter), the installation force is critical. The installation torque for the sensor (transmitter) must only be applied to the shaft (hexagonal), and no force should be applied to the sensor (transmitter head).

The housing of the sensor (transmitter) must be kept away from high-temperature areas. Use mounting brackets to secure the housing to the bracket (refer to Figure “D”). For flange mounting, depending on the characteristics of the medium, appropriate sealing gaskets should be added to the sealing surface.

1/2-20 UNF / M14×1.5 = Maximum starting torque: 40 Nm

M18 x 1.5 = Maximum starting torque: 50 Nm

Flange mounting = Maximum starting torque: 50 Nm

Unloading

The pressure sensor (transmitter) must be removed under heated conditions (plastic melting point). When removing the sensor (transmitter), make sure that the diaphragm is not exposed to pressure. The force used to unload the sensor (transmitter) must only be applied to the shaft (hexagon) and no force should be applied to the sensor (transmitter) head.

Threaded mounting method opening

02 Precautions

#1 Scope of Application

Melt pressure sensors (transmitters) are designed specifically for monitoring the pressure of liquids, gases, or viscous substances at high temperatures. These substances must be in a liquid, gaseous, or viscous flow state. Under normal operating conditions, the pressure must not exceed the upper limit of the measurement range, and the instantaneous pressure must not exceed 150% of the upper limit of the measurement range (based on the diaphragm surface). Any use beyond the aforementioned application scope is not compliant.

#2 Hazardous Areas

In the installation sealing area of the melt pressure sensor (transmitter), there is a risk of medium leakage if the pressure transmitter is not properly installed or removed.

#3 Safety and Storage

Pressure sensors (transmitters) are typically packaged individually. The sensing diaphragm is protected by a protective cap at the threaded end of the rigid rod. This protective cap must remain securely fastened at all times during storage and should only be opened during installation.

03 Zero Adjustment Function and Wiring Configuration

Zero Adjustment Function

After the pressure sensor (transmitter) has been installed on the pipeline, the electrical connections must be made according to the wiring diagram shown below. The CM series pressure transmitters are equipped with an integrated amplifier circuit (the sensor does not have an amplifier circuit). The zeroing process must be performed when the pipeline is heated and the pressure is zero. The zero point is adjusted by activating the automatic zeroing function, which is initiated by a short circuit connection of the corresponding wires (see wiring diagram). Alternatively, a magnetic pen can be used to achieve zeroing by holding it against the zeroing mark on the housing for 3–5 seconds (see figure below); the mV signal does not currently support this function and must be zeroed via the downstream instrument. Then perform an 80% check on the output signal (see wiring diagram); the pressure sensor (transmitter) will provide a signal corresponding to the standard 80% measurement value.

Wiring method

Transmitter series: 0-10 V, 4-20 mA

Sensor series: 3.33 mV/V

Cable wires must use shielded cables, with each core wire approximately 0.3mm², and a heat resistance temperature of no less than 105°C. Each core wire connection terminal should be isolated and protected with heat-shrink tubing. The shielding wire must be connected to the metal connector. When welding cables, special care must be taken; otherwise, it may cause signal transmission errors or damage the product. It is recommended to use pre-welded specialized cables from GRAEFF. For any excess wires inside the cable, each wire should be individually wrapped with insulating tape.

For other connector specifications, please contact the factory.

Phone: 400 616 0338

Email: info@graeff.net

Website: www.graeff.net