What does ”Dry running a Pump” mean?
Dry Running is an undesirable condition which affects most pump designs and is characterised when a pump operates without an adequate amount of fluid. In most pump technologies, this leads to cavitation and critical damage to the internal pumping elements such as impellers, lobes, gears, casings, seals & bearings.
How is dry running caused?
Dry running is usually related to how the pump is operated, monitored & controlled which is typically a result of human error. Companies generally rely on their operators to monitor the pumps on the line, however, problems will arise when a pump is unintentionally left running for prolonged periods of time after the intended operation has been completed. For example, during offloading of a tanker, an operator may leave the pump unattended whilst the tanker is being evacuated and the pump may over-run when the tanker is empty thus resulting in damage to the pump internals.
Why is it important to avoid?
Dry Running can cost companies millions of pounds a year when considering operational spares costs, lost sales due to poor performance, downtime & affiliated loss in production, as well as sub-contracted maintenance costs. According to World Pumps, due to improving economies and estimated increases in fuel production, sales of fluid handling pumps are forecast to increase approximately 5.5% annually to $84 Billion in 2018. As a result, the costs affiliated with dry running will also increase substantially.
How would I avoid dry running?
When using most pump designs, such as Rotodynamic as well as Reciprocating and Rotary Positive Displacement Pumps, most companies need to install protection and control devises on the pumps and system to ensure that the pump is stopped immediately after the pumping operation is complete, or in the absence of fluid at the pump suction or source.
Generally, there are 3 different methods used for protecting pumps from Dry Running:
- Pressure or Level Switch Protection: Pressure Switches fitted to the suction pipe or port of the pump(s) or Float Switches/Electrode Relays in the Supply tank
- Pressure Transmitter Protection: Measurement of the inlet pressure of the pump(s) by means of an analogue pressure transmitter
- Level Transmitter Protection: Measurement of the supply tank fluid levels by means of an analogue level transmitter such as an Ultra-Sonic Level Sensor.
Engineers on-site and Operators spend significant amounts of time ensuring pumps are properly installed & primed, significantly increasing the cost and complexity of the installation. However, despite all these efforts, the ever-present possibility of human error, malfunctioning control and monitoring equipment, unpredictable events & improper use of equipment means that Dry Running is never completely eradicated. As a result, plant owners are constantly in search of technology and solutions which can prevent or avoid the costly and damaging effects of Dry Running in order to reduce maintenance costs, increase throughput and alleviate pressures put onto operators to constantly monitor, control and protect their equipment on the line.
What can Tapflo provide to overcome problems associated with dry running?
Apart from the standard accessories and equipment required to protect and control pumping equipment that is affected by Dry Running, such as Temperature & Pressure Sensors and complex & often expensive Sealing Systems, Tapflo has 2 pump solutions available which don’t need any of these and can run dry indefinitely without damaging the pump: Peristaltic Pumps & Diaphragm Pumps.
Due to their design & construction, both of these pumping technologies are able to operate under dry conditions without experiencing the common wear problems associated with Dry Running. Not only does this alleviate the pressures put onto operators, but it also simplifies the pumping system and reduces the cost of installation and ownership significantly. Of course, these designs, on their own, do not overcome the energy costs affiliated with overrunning equipment, so to make it even better we can offer dry run protection devices (air & electrically driven) to automatically stop our pumps when the pumping process has been completed.
In summary, Tapflo UK have a full range of pumping solutions which can either protect equipment from Dry Running or indeed avoid problems associated with Dry Running completely! Let’s discuss your options today.