Wireless technology is part of our everyday lives in the home and office. From garage door openers and television remote controls, to cellular telephones and wireless Internet access, radio frequency (RF) technology has been accepted as a reliable, efficient and easy-to-use medium.

In recent years, this technology has begun the logical progression from the home and office into the industrial world-onto the plant floor and into the field. It adds convenience, reduces installation time and provides solutions to common problems. Replacing or eliminating cables with wireless technology has many attractive features beyond the obvious installation speed (hours versus days/weeks) and cost savings (labor, permits, material). However, debate continues about the reliability of wireless products for control-based applications.

Wireless Reliability

Wireless modems and radio telemetry devices have been used in control systems of mission critical pumps for more than 30 years, yet fear of the unknown remains. There have been thousands of successful wireless implementations in open loop applications, which require data delivered in an acceptable one to two seconds. Alternatively, a closed loop application requires micro or millisecond response times and is not as well suited for wireless. It is important to note the difference between a deterministic, or time-critical, application and one that requires only high data reliability.

The nature of the RF environment dictates that there is no absolute guarantee that any given piece of data will be successfully transmitted and received over the air. However, a well-designed radio will have built-in error checking and retry capabilities that continue sending a piece of information until it is successfully received. This makes it possible to send important data over a wireless link, as long as the entire system can tolerate some amount of latency or delay.

Wireless Advantages

A wireless network can provide technical advantages and cost benefits for pump monitoring and control applications. Installing wireless systems to replace both communication and sensor signal cabling can reduce the time it takes to engineer and develop the expansion or construction of a pumping plant.

The upfront cost of a wireless system is often immediately lower than cabling and conduit costs, and the savings in labor and permits are enormous. A signal that previously took days to bring online using traditional wiring can now be commissioned within hours. With this time savings and flexibility, maintenance crews can deploy wireless nodes for temporary troubleshooting or add "stranded" measurement points for safety or improved efficiency.

Utilities are reducing costs and improving productivity to survive in a more competitive and economically challenged environment. Acquiring data and using that data to control or make decisions can reduce operations cost and optimize important assets like pumps and motors.

To maximize pump efficiencies and balance the run times on pumps, most systems come with on-board, standalone control capability. Even so, operators cannot always be onsite to ensure that run-time conditions are acceptable. To monitor and control pumps remotely, most companies communicate through fiber, copper or some hard-wired cable. Ideally, important sensors that monitor suction/discharge pressure, tank levels, system pressure, flow rates and temperatures can be tied back to the pump controller via wire. A hard-wired network of pump control panels is also ideal if it can communicate cost-effectively.

But in a world that is not always ideal, wireless can be the next best thing to wire. In fact, many locations have found wireless connections provide a more reliable connection than a wired circuit.

Managing lift stations is one of the biggest problems water utility operators face. Lift stations are built-in remote locations spread out around cities and business areas. A lift station typically includes two pumps that pump sewage into massive underground tanks. Clogging or infiltration can gradually reduce a pump's efficiency, until the pump eventually stops operating.

When a pump stops, the old-fashioned system alarms the site; however, at this point, it might be too late. Diagnosing and repairing the problem might take too long, causing spillage to occur. Often, the pumps do not completely fail; rather, they lose efficiency. The old-fashioned system will allow the anomaly to go unnoticed until a spill is detected by residents or other means. Spills reported by the public often lead to fines, lawsuits and even criminal charges for the wastewater engineer or superintendent.

Tougher EPA and Clean Water legislation have dramatically increased the need for the monitoring and control of sewage collection systems. Combined Sewer Overflow (CSO) applications currently require the monitoring of retention basins, sewer levels and the control of pumps, valves and backwater gates. Industrial wireless solutions have become the preferred option for these applications.

A spill occurs every day somewhere in America. Cost ranges from $50,000 to $100,000, not to mention the seemingly irreparable environmental damage. The cost includes the price of pumping out the lift station, new pumps, rush shipping of parts, area cleanup, overtime and other ancillary charges. Wireless pump control products can prevent a spill altogether, which reduces downtimes and contains a problem before it hits the headlines.