Submersible Pressure Transducer Maintenance

Submersible pressure transducers work exactly like other pressure transducers when measuring the amount of pressure in a given area. What separates these devices is the fact that they are placed underwater to record their measurements. Hydrostatic level measurement with submersible pressure transducers has become one of the most popular methods when it comes to liquid measurement. The popularity of this method can be attributed to its simplicity from easy installation to reliability.

However, despite the perks and simplicity of the device, there is one factor in particular that hinders its dependability. The functionality of the submersible pressure transducers relies on the maintenance of the device’s vent tube. An accumulation of condensation or any sort of moisture in the device is disastrous in regards to the accuracy of the device and should be avoided at all costs. There are precautions that one can take in order to preserve the vent tube from becoming susceptible to this type of buildup. So what are they?

Vent Tubes

Because submersible pressure transducers are at the bottom of a tank or well, the sensor must be vented to the atmospheric pressure. However, because they are underwater, a submersible pressure transducer’s vent tubes must run along the entire cable, being cut off where the electrical wires at the end of the cable run. Standard pressure instruments are simply vented through their housing unit, giving the vent tube a significant amount of importance to submersible transducers.

Another factor to consider with these vent tubes is that they are directly associated to the components. With that said, if condensation or any kind of liquid were to build up, it could compromise the entire device. There are three standard precautionary measures taken to reduce these risks, which are using either bellows, desiccant cartridges, or hydrophobic caps.

Preventative Methods
The bellows method is sealing the vent tube so that your zero pressure references is inside the bellow of the device. Here, the bellows are able to decompress and compress contingent on pressure changes. This method allows the vent tube to stay protected from liquid while also being able to fluctuate to the changes in atmospheric pressure.

Despite the protection the bellows method gives the vent tube, it has one flaw. Unfortunately, the readings that the bellows give are not barometrically sound. Overall, this method is a better alternative to using a completely sealed sensor, but is not the perfect in administering perfect readings.

Desiccant Cartridge

In the simplest terms, desiccant cartridges are devices used for products and instruments that are sensitive or susceptible to moisture and humid environments and generally have a molecular sieve fill or a silica gel fill. Applying these devices to submersible pressure transducers, the desiccant cartridge is connected towards the end of the vent tube and stored alongside other controls.

Yet, the drawback to this method of protection is that is requires high maintenance in comparison to other methods. Contingent on the environment in which it is placed, the device requires to be replaced every couple months.

Hydrophobic Caps

Hydrophobic vent caps are small plastic tubes with one end open and the other end enclosed by a hydrophobic membrane. These are regarded as one of the most pragmatic options for those looking to protect their submersible pressure transducers due to the fact that they do not need to be replaced as well as being able to orate real atmospheric conditions.

The device comes with two major downfalls. First, hydrophobic caps do not necessarily take out moisture. With that said, if moisture is already present in the tube, it will remain there. Secondly, is moisture that collects itself to the outside of the caps’ membrane can seal off the tube. Luckily, this can be prevented by placing the tube so that the caps is both elevated and facing down.

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