YOKOGAWA pressure transmitter EJX310B

YOKOGAWA  pressure transmitter EJX310B

A pressure transmitter is a device that converts pressure into pneumatic or electric signals for control and remote transmission

It can convert the physical pressure parameters such as gas and liquid sensed by the pressure measuring element sensor into standard electrical signals (such as 4-20mADC), to supply secondary instruments such as indicator alarms, recorders, regulators, etc. for measurement, indication, and process adjustment.

Working principle:

The electrical component for sensing pressure in a pressure transmitter is generally a resistance strain gauge, which is a sensitive device that converts the pressure on the measured object into an electrical signal. The most commonly used types of resistance strain gauges are metal resistance strain gauges and semiconductor strain gauges. There are two types of metal resistance strain gauges: wire shaped strain gauges and metal foil shaped strain gauges. Usually, strain gauges are tightly bonded to a mechanically strained substrate through a special adhesive. When the substrate undergoes stress changes, the resistance strain gauge also undergoes deformation, causing a change in the resistance value of the strain gauge and a change in the voltage applied to the resistance

Main performance:

1. The tested medium is widely used and can measure oil, water, and paste substances compatible with 316 stainless steel and 304 stainless steel, with a certain degree of anti-corrosion ability;

2. High accuracy, high stability, selection of imported original sensors, good linearity, and high temperature stability;

3. Small size, light weight, easy installation, debugging, and use;

4. Stainless steel fully enclosed shell, good waterproof;

5. The pressure sensor directly senses the measured liquid level pressure and is not affected by medium foaming or sedimentation.

Main advantages:

1. Pressure transmitters have the characteristics of reliable operation and stable performance;

2. Dedicated V/I integrated circuit, with fewer peripheral components, high reliability, simple and easy maintenance, small size, light weight, and extremely convenient installation and debugging;

3. Aluminum alloy die cast shell, three end isolation, electrostatic spray protective layer, sturdy and durable;

4. 4-20mA DC two wire signal transmission with strong anti-interference ability and long transmission distance;

5. Three types of indicator heads, LED, LCD, and pointer, make on-site readings very convenient. Can be used to measure viscous, crystalline, and corrosive media;

6. High accuracy and stability. In addition to using laser correction for imported original sensors, the comprehensive temperature drift and nonlinearity of the entire machine within the temperature range of use are finely compensated.

Instructions for use:

Daily maintenance

1. Check the size of the installation hole: If the size of the installation hole is not appropriate, the threaded part of the sensor is easily worn during installation. This not only affects the sealing performance of the equipment, but also prevents the pressure sensor from fully functioning, and may even create safety hazards. Only suitable mounting holes can avoid thread wear (thread industry standard 1/2-20 UNF 2B), and mounting hole measuring instruments can usually be used to detect mounting holes and make appropriate adjustments.

2. Keeping the installation holes clean: Keeping the installation holes clean and preventing molten material blockage is crucial for ensuring the normal operation of the equipment. Before cleaning the extruder, all pressure sensors should be removed from the barrel to avoid damage. When removing the sensor, molten material may flow into the installation hole and harden. If these residual molten materials are not removed, it may cause damage to the top of the sensor when reinstalled. The cleaning tool kit can remove these residual molten materials. However, repeated cleaning processes may deepen the damage caused to the sensor by mounting holes. If this situation occurs, measures should be taken to raise the position of the sensor in the installation hole.

3. Choose the appropriate location: When the installation position of the pressure sensor is too close to the upstream of the production line, unmelted materials may wear the top of the sensor; If the sensor is installed too far back, there may be a stagnation zone of molten material between the sensor and the screw stroke, where the molten material may degrade and the pressure signal may be distorted; If the sensor is too deep into the barrel, the screw may touch the top of the sensor during rotation and cause damage. Generally speaking, sensors can be located on the barrel in front of the filter, in front and behind the melt pump, or in the mold.

4. Carefully clean; Before using a wire brush or special compound to clean the extruder barrel, all sensors should be removed. Because both cleaning methods may cause damage to the vibration film of the sensor. When the cylinder is heated, the sensor should also be removed and wiped on top with a soft cloth that will not cause wear. At the same time, the holes of the sensor need to be cleaned with a clean drilling machine and guide sleeve.

Proper use

During the use of pressure sensors, attention should be paid to the following situations:

1. Prevent the transmitter from coming into contact with corrosive or overheated media;

2. Prevent sediment from settling inside the conduit;

3. When measuring liquid pressure, the pressure tap should be located on the side of the process pipeline to avoid sediment accumulation;

4. When measuring gas pressure, the pressure tap should be located at the top of the process pipeline, and the transmitter should also be installed at the top of the process pipeline to facilitate the accumulation of liquid into the process pipeline;

5. Pressure pipes should be installed in areas with low temperature fluctuations;

6. When measuring steam or other high-temperature media, it is necessary to connect a buffer tube (coil) or other condenser, and the working temperature of the transmitter should not exceed the limit;

7. When freezing occurs in winter, the transmitter installed outdoors must take anti freezing measures to prevent the liquid in the pressure inlet from expanding due to ice volume, which may cause damage to the sensor;

8. When measuring liquid pressure, the installation position of the transmitter should avoid liquid impact (water hammer phenomenon) to prevent damage to the sensor due to overpressure;

9. When wiring, thread the cable through the waterproof joint (accessory) or flexible tube and tighten the sealing nut to prevent rainwater from leaking into the transmitter housing through the cable.

YOKOGAWA 横河 压力变送器EJX310B

压力变送器是一种将压力转换成气动信号或电动信号进行控制和远传的设备

它能将测压元件传感器感受到的气体、液体等物理压力参数转变成标准的电信号(如4~20mADC等)，以供给指示报警仪、记录仪、调节器等二次仪表进行测量、指示和过程调节。

工作原理：

压力变送器感受压力的电器元件一般为电阻应变片，电阻应变片是一种将被测件上的压力转换成为一种电信号的敏感器件。电阻应变片应用最多的是金属电阻应变片和半导体应变片两种。金属电阻应变片又有丝状应变片和金属箔状应变片两种。通常是将应变片通过特殊的黏合剂紧密地粘合在产生力学应变基体上，当基体受力发生应力变化时，电阻应变片也一起产生形变，使应变片的阻值发生改变，从而使加在电阻上的电压发生变化

主要性能：

1、使用被测介质广泛，可测油、水及与316不锈钢和304不锈钢兼容的糊状物，具有一定的防腐能力;

2、高准确度、高稳定性、选用进口原装传感器，线性好，温度稳定性高;

3、体积小、重量轻、安装、调试、使用方便;

4、不锈钢全封闭外壳，防水好;

5、压力传感器直接感测被测液位压力，不受介质起泡、沉积的影响。

主要优点：

1、压力变送器具有工作可靠、性能稳定等特点;

2、专用V/I集成电路，外围器件少，可靠性高，维护简单、轻松，体积小、重量轻，安装调试极为方便;

3、铝合金压铸外壳，三端隔离，静电喷塑保护层，坚固耐用;

4、4-20mA DC二线制信号传送，抗干扰能力强，传输距离远;

5、LED、LCD、指针三种指示表头，现场读数十分方便。可用于测量粘稠、结晶和腐蚀性介质;

6、高准确度，高稳定性。除进口原装传感器已用激光修正外，对整机在使用温度范围内的综合性温度漂移、非线性进行精细补偿。

使用说明：

日常维护

1、检查安装孔的尺寸：如果安装孔的尺寸不合适，传感器在安装过程中，其螺纹部分就很容易受到磨损。这不仅会影响设备的密封性能，而且使压力传感器不能充分发挥作用，甚至还可能产生安全隐患。只有合适的安装孔才能够避免螺纹的磨损(螺纹工业标准1/2-20 UNF 2B)，通常可以采用安装孔测量仪对安装孔进行检测，以做出适当的调整。

2、保持安装孔的清洁：保持安装孔的清洁并防止熔料堵塞对保证设备的正常运行来说十分重要。在挤出机被清洁之前，所有的压力传感器都应该从机筒上拆除以避免损坏。在拆除传感器时，熔料有可能流入到安装孔中并硬化，如果这些残余的熔料没有被去除，当再次安装传感器时就可能造成其顶部受损。清洁工具包能够将这些熔料残余物去除。然而，重复的清洁过程有可能加深安装孔对传感器造成的损坏。如果这种情况发生，就应当采取措施来升高传感器在安装孔中的位置。

3、选择恰当的位置：当压力传感器的安装位置太靠近生产线的上游时，未熔融的物料可能会磨损传感器的顶部;如果传感器被安装在太靠后的位置，在传感器和螺杆行程之间可能会产生熔融物料的停滞区，熔料在那里有可能产生降解，压力信号也可能传递失真;如果传感器过于深入机筒，螺杆有可能在旋转过程中触碰到传感器的顶部而造成其损坏。一般来说，传感器可以位于滤网前面的机筒上、熔体泵的前后或者模具中。

4、仔细清洁;在使用钢丝刷或者特殊化合物对挤出机机筒进行清洁前，应该将所有的传感器都拆卸下来。因为这两种清洁方式都可能会造成传感器的震动膜受损。当机筒被加热时，也应该将传感器拆卸下来并使用不会产生磨损的软布来擦拭其顶部，同时传感器的孔洞也需要用清洁的钻孔机和导套清理干净。

正确使用

压力传感器使用过程应注意考虑下列情况：

1、防止变送器与腐蚀性或过热的介质接触;

2、防止渣滓在导管内沉积;

3、测量液体压力时，取压口应开在流程管道侧面，以避免沉淀积渣;

4、测量气体压力时，取压口应开在流程管道顶端，并且变送器也应安装在流程管道上部，以便积累的液体容易注入流程管道中;

5、导压管应安装在温度波动小的地方;

6、测量蒸汽或其它高温介质时，需接加缓冲管(盘管)等冷凝器，不应使变送器的工作温度超过极限;

7、冬季发生冰冻时，安装在室外的变送器必需采取防冻措施，避免引压口内的液体因结冰体积膨胀，导至传感器损坏;

8、测量液体压力时，变送器的安装位置应避免液体的冲击(水锤现象)，以免传感器过压损坏;

9、接线时，将电缆穿过防水接头(附件)或绕性管并拧紧密封螺帽，以防雨水等通过电缆渗漏进变送器壳体内。