Since their introduction into the industry, the use of electronic gas detectors has been traditionally associated with the use of pumps; however, to date, numerous workers continue to discuss the most appropriate time and situation in which these pumps should be used. It is therefore typically understood that each gas monitor should have a pump to optimize its accuracy, enhance its overall response time and improve the ability of pumps to accurately detect gas concentrations. Although these associations are not entirely true, these properties of pumps have supported the notion that pumps improve the ease and safety of performing most tasks.
Reasons to Use a Pump with a Gas Detector
A pumped gas monitor allows air to be withdrawn from a given unknown location, or during a situation in which a potentially toxic or flammable gas can be present. As a result of its use in these situation, pumps are associated with improving the general safety associated with performing numerous operations. Once the sampling procedure is complete and air safety has been fully established, users can then safely enter the analyzed location to complete any necessary work.
Another type of situation in which pumps are useful involve vessels that are 30 feet in length or greater, but not too tall, thereby causing working space to be increasingly confined. During this type of situation, a pump that has been equipped with an extensible probe can be used to slowly explore the confined space during which the attached probe tests any air in front to determine its safety for the user to explore further into the cavity.
In situations where pumps are being used to investigate very tall narrow vessels that only have accessible space located from above the vessel, it would be ideal to utilize a pump with long tubing in order to evaluate the completeness of emptying of the space of all hazardous gases before the worker enters. For this type of situation, a pumped gas monitor can successfully improve the safety and convenience of the given operation, particularly when detection of a toxic gas is necessary. More specifically, the use of pumped gas monitors in these situations do not affect the range or effectiveness of detectable gases since this factor is attributed to the type of gas that comes in direct contact with the sensors of the monitor.
It is important to note that the utilization of a pump is not associated with increases the chance of monitors coming into contact with harmful gases. Rather, pumping allows for the remote testing of the air from places that are at a significant distance away from the monitor. In situations where two adjacent gas monitors are being tested, with one having a pump that is not attached to tubing and one without, both will provide the same readouts since the pump does not increase the speed of hazardous gas detection as compared to the other unit.
Pumped gas monitors help to keep you out of areas where potentially harmful gases may be lurking.
Reasons Not to Use a Pumped Monitor
The use of a pump on a gas monitor can significantly increase the size and bulk of the detector without increasing its sensitivity of detection. Note that this can potentially cause problems in situations where the user requires gas monitors to be worn throughout typically wear working hours, as this increase in size and weight of the detector can cause a physical burden to the user. In addition, an increase in the size of the pump is also associated with a limited battery life and overall run time. As a result, it would be more practical for a smaller, lighter and highly efficient detector that exhibits an extended battery life throughout the full shift to be used in these situations.
Other Factors in Pump Usage
If it is determined that your gas detector requires a monitor with a pump, other components can be incorporated to optimize the monitor’s performance and resistance to potential damage. For example, the utilization of either a lightweight polycarbonate or stainless-steel probe that can be easily extended is essential in the event that a pumped monitor is being used to enter a confined space. Additionally, a high-temperature stable probe may also be useful for this particular situation.
Tubing, typically compose of urethane material, is also a necessary component during the monitoring and inspection of vertical narrow cavities. Typically, these types of tubing are capable of handling a wide variety of gases, except for chlorine and chlorine dioxide, hydrogen chloride and volatile organic compounds (VOCs), all of which are absorbed by this material and therefore causes lower gas concentration levels to be read. As a result of this limitation, teflon-lined tubing remains the first choice when these types of gases are being monitored.
When pumps are equipped with tubing, it is always required that the pump be switched on for a period of time that allows for gas to run through the complete tubing, from one end to the other, and then to pass into the sensors by diffusion. Although this may appear to be a lengthy process, it is estimated that it only requires approximately two seconds for gas to be moved through each foot of tubing, as well as for an additional two minutes during which the tubing comes in contact with the sensor and stabilizes. In conclusion, for example, a 30-foot length of tubing is expected to produce readouts that require a total duration of approximately three minutes until gas can be successfully sampled at the end of the tubing.
Again, in the situation where a pump is being used, it is also mandatory that both a dust filter and water stop is incorporated at the end of the probe or tubing to prevent dust and any other particles that may potentially damage the sensor from entering the tubing. Additionally, it is also important to prevent the inadvertent drawing in of water into the pump motor in the event that the tubing end comes into contact with a liquid.
Pumped gas monitors are a useful tool that can be used to reduce the potential harm from occurring in a variety of applications, such as a water treatment plant during which pumps are useful for confirming the absence of gases present within a tank prior to it being subjected to unnecessary maintenance checks, or in a refinery, within which it is required for managers to investigate for the presence of leaks present within the valves and pipelines in otherwise inaccessible locations. However, it is important to note that the use of monitors without a pump is a better choice for certain applications, such as personal gas detectors that do not require the sampling of gases from remote locations.
This information has been sourced, reviewed and adapted from materials provided by Industrial Scientific.
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