Measuring Instruments to Monitor Wastewater Pumps for Performance, Safety, and Savings

Pressure Instruments for Wastewater Pumps

Pressure gauges and sensors at suction and discharge nozzles, delivery pipes, release valves, control circuits, and other locations on a pump help monitor the equipment’s condition and ensure that it’s operating properly.

Pressure at the suction side, to prevent cavitation

Cavitation is the generation of vapor bubbles, which occur in high-velocity liquids. When these bubbles collapse, the result is pressure spikes. Cavitation can also occur if the local pressure drops below the vapor pressure of the liquid and then rises above it. To avoid this condition, the net possible suction head available (NPSHa) has to be greater than the net possible suction head required (NPSHr).

Monitoring the suction head (pressure in terms of the water column) can help identify problems that damage pumps. The A-10 pressure transmitter features a piezoelectric sensor or thin-film technology, making it highly resistant to pressure spikes and vibration. It has an all-welded stainless steel measuring cell and does not need any soft sealing. A variety of available electrical process connections meets the requirements of almost any application.

Pressure at the discharge side, to ensure proper operations

Both underpressure and overpressure on the outlet side reduce a power plant’s efficiency. All XSEL^® models – 21X.34, 23X.34, and 26X.34 – feature a Bourdon tube design and movement with hardened components that reduce stress and wear. The innovative XSEL^® process pressure gauge exceeds pressure gauge performance testing standards ASME B40.100 and EN 837-1. And it’s safer, too: The XSEL^® has a fire-resistant case according to flammability rating UL 94, V-0 test procedures.

XSEL^® process pressure gauge movements are Swiss-made, producing one of the most precise and reliable movements available today. WIKA’s industry-best warranty on all XSEL^® process pressure gauges include a standard five-year warranty on the pressure gauge and a 10-year warranty on the pressure system. The XSEL^® process gauge sets a standard of value as well: It is an economical solution for most processing applications since it reduces downtime from having to regularly replace worn-out instruments.

Differential temperature and pressure between the suction and the discharge fluid, to assess pump efficiency

To make sure a pump is working at optimal capacity, technicians can place highly accurate temperature sensors and pressure transmitters at both the suction and discharge sides. If the pump isn’t operating as efficiently as it can be, there will be a drop in pressure and temperature. This is thermodynamic monitoring, which does not require measuring the actual flow rate to determine efficiency.

The A-10 pressure transmitter is precision-engineered for excellent performance. The standard model has a non-linearity (BFSL) of ≤±0.5% of span, and there’s an option for ≤±0.25% of span. This versatile and rugged transmitter can withstand a wide range of temperature and pressure conditions, as well as the extreme shock and vibrations found in power plants.

The TR10 series of RTD sensors can be mounted into a thermowell, or directly into the process with a spring-loaded compression fitting for easy installation and replacement. The TR10 has the option of a transmitter to convert the resistance signal into an analog or a digital output, which can be easily customized to a variety of conditions.

Differential pressure at filters and strainers, to assess debris accumulation

If pressure drops at the discharge side, that’s a good indication the strainer or filter needs to be cleaned or replaced. Monitoring the pressure differential between the inlet and outlet of a pump can also indicate overall efficiency and help identify conditions where cavitation is likely to occur.

The SP007 differential pressure transducer is fully configurable. Users have a choice of six pressure ports, five electrical connections, and a voltage or current output to match the needs of their applications. The SP007 has a standard accuracy of 0.25% and an optional high accuracy of 0.1%.

Temperature Instruments for Wastewater Pumps

Resistance thermometers (RTDs) on pumps and motors help detect temperature changes that can warn operators of potentially dangerous and costly issues.

Temperature at the bearings, to prevent overheating

A change in the bearing temperature of a pump and/or motor can indicate a developing failure or a change in loading. The compact TR58 bearing RTD sensor is designed for areas where space is an issue. It uses thin-film technology and responds extremely fast. With no moving parts, it is vibration-resistant and perfect for measuring temperature in thrust bearing plates, shafts, and motor windings. The TR58 can be spring loaded into the bearings’ housing or held in position with a high temperature epoxy resin.

Flow Instruments for Wastewater Pumps

A pump is “dry running” – in a nearly empty pipe condition – when the suction side doesn’t receive enough fluid. When the pump operates with no flow at all, it is “dead-headed.” Both conditions can cause the pump to overheat and fail.

 

Flow at the suction side, to signal low fluid levels

Ideal for monitoring cooling systems, the FSD-4 electronic flow sensor offers full flexibility in controlling flow based on a liquid’s velocity. The switch points are easy to configure using the 3-button instrument panel and large LED display, or with the IO-Link option. This advanced flow sensor has analog output signals and two digital switches, one of which can be programmed for temperature switching. There are no moving parts, which means the FSD-4 won’t ever suffer from wear and tear.

 

Wireless Sensors for Predictive Monitoring and Maintenance