Looking for a simple way to reduce cost of operation?  Have you viewed your energy bill, lately?

The cost of energy has been skyrocketing.  Water and wastewater utilities are becoming aware of the large cost of energy bills as part of their bottom line.  Much of the cost of energy at these utilities is directly related to electric motors.

Energy audit at pumping station in Mequon, Wis.

Here are statistics from the Department of Energy (DOE):

• Nearly 25% of all of the nation’s electricity demand comes from industrial motor systems
• Over 50% of pump “life-cycle-costs” result from energy and maintenance expense
• Less than 15% of pump “life-cycle-costs” are initial purchase costs
• Energy savings of 20% or more are possible with systems optimization

In addition, power and efficiency levels are defined – allowing comparison to published data for the pumps as installed.  It’s like having the DNA for pump/motor combinations in actual field conditions.  And, the data is now available for comparison to future measured values – tracking performance in a scientific approach to optimizing performance.

In addition to awareness of power consumption, operators/owners of utilities need to be aware of the quality of the power they are buying.  Quality of electric power includes variation in power across the legs of three phase lines and variation in the quantity of variability in the sine wave being provided (sometimes containing harmonic variations).  The consumer of electric power rarely knows the quality of power being purchased at his metered location.  The quality of power being provided will directly affect the life span and operating characteristics of machinery being operated in the consumer’s plant.

Fortunately, there are simple instruments which a consumer of electricity can use to make quality and quantity checks for the power being purchased. I recently had the opportunity to borrow a “power pad” by Rockwell Automation/Allen Bradley in conjunction with a pump station audit for the City of Mequon, WI. PowerPad offers a wide assortment of measurement parameters in one compact device. It can determine both quality and quantity of power being provided to the end user and provides both qualitative and quantitative metrics to offer ways to improve upon the effective use of power while minimizing consumption by measuring and reporting. A photo of a typical field set up – with laptop, PowerPad and whiteboard at Mequon is depicted in the photo at left.

City of Mequon, Wis. Pioneers in Defining Pumping Station Performance Metrics

Actual recording of energy consumption for one pump cycle at Mequon, WI

The city of Mequon, WI – home of Allen Bradley’s Drives and systems division – elected to be pro-active in their defining the metrics of performance for their 21 wastewater pumping stations.  As part of their “metrics” project, they asked their consultant to provide energy consumption values for the pumps at their main pumping stations.  The Rockwell PowerPad portable power monitor was the perfect solution to their needs.  Each pump was run at design flow conditions and power curves were produced (an example of power/watts vs time for one pump cycle is shown in the graph) which defined energy consumption for the design conditions.

Thanks to Sean Schmelzer, P.E., Rockwell Automation, Allen Bradley Division for providing the PowerPad for this study at no cost.

Fred Schneeberg, Mequon Utilities Superintendent, for helping us through our first official pump station audit.

David Rice, Electrical Engineer, Port Washington, Wis. for sorting through the hardware and software to refine the field data.

Take care,
Don

Don Voigt, P.E.
Systems Engineer

Pumping systems offer a tremendous opportunity for improvements in Operation and Maintenance (O&M) costs.

Obviously, new designs have a clean slate, so to speak, and the insightful designer is offered a broad spectrum of design alternatives and associated benefits (or not) for the end user/operations staff.  In such situations, the key parameter or benchmark should always keep “life-cycle-costs” in its solutions or recommendations.

Field conditions can create difficulty in obtaining valid system data

Existing pumping stations, likewise, hold a wide reservoir of potential for improvements – ranging from motor upgrades to control system replacements.  An important element of any upgrade will be the field survey of existing systems.  Such a survey should have a well developed plan or strategy from the onset.  An integral part of the plan would include measurement of key operating parameters.  Listing these and preparing a tabulation for use in later design phases will be important in its variety and its specificity.  Here are suggested measurements for pumping systems – just as a starter:

1. Motor amps and watts under various load and no-load conditions
2. If variable speed drives, take multiple measurements at corresponding points with pump discharge pressure, flow, and watts/amps recorded at specific flows/heads.
3. Note location of the pressure gauges and flow measurement devices ( a photo would be the optimum for this).
4. Measure static pressure with the pump off…be sure you have the gauge located where it can read static pressure (ahead of any check valve).
5. Take measurements 1, 2, and 3 with pumps “off”, pumps on  and multiple pumps on (in multiple pump stations).
6. Note motor model and serial numbers; likewise for pumps and controls.
7. Borrow a portable watt meter and record flow (you may also need a portable flow meter), watts and speed for at least a few days in sequence.
8. Request digital watt meter data for the pumping station from the electric power company serving your community or utility.  This data can reveal unusual conditions which might be triggering higher peak demand charges.
9. Obtain 12 months of electric utility bills for the pumping station and examine these for demand charges and other rate premium charges.

In his famous books, Steven Covey states it best:

“Begin with the end in mind.  Particularly in a field study in field conditions, a good set of tools and a firm set of data requirements can be the difference between exceptional and “just average” for pumping station systems upgrades.”

Don’t leave home without it!

Don

This pump was operating against a partially closed valve for years without anyone knowing there was a problem.

Over the years, I’ve read a number of articles in the popular water/wastewater trade journals – authored by the “Pump Guy” (Larry Backus of Backus Inc). Since he seems to have such simple answers to apparently complex problems, I recently jotted him an email – asking about his recommendations for “tools” for doing a pump survey for a typical client. Here is the dialog:

Dear Larry,
I really always appreciate your articles in the various technical journals in our industry. So practical and so unique in their perspectives.

The article in the August issue of Flow Control refers to the importance of “systems” in looking at “problems” and I agree 100%. Look at the following blog to see the name and the recent article:
http://equipintegration.com/wordpress/

On a related issue regarding pumps…..do you have a list of “recommended tools” for conducting field evaluations of pumps? Such as a vibration meter, an amp meter, watt meter, pressure gage, speed meter and the like? It would be nice to have a suggested list of tools with example manufacturers of the tools to help a person put together a kit.

Don

Hello Don,
Glad you like the Pump Guy articles. I enjoy writing the column.

As for the recommended tools;
I used to operate a pump rebuild shop. We had 3 pick-up trucks loaded with equipment and tools to attend to the process pumps and motors of our clients. We carried amp meters, alignment equipment, vibration meters, gauges, portable cranes, chain hoists, a complete set of air powered tools, lubricants, gaskets, spare bearings and seals, spare nuts and bolts, etc. to disassemble, repair, load, and off-load pumps and parts onto the trucks.

Today, I travel with my laptop, safety glasses and a hard hat. I visit a process plant or power station as a pump consultant. I tell the engineer to install his equipment (vibration meters, flow meters, gauges, amp meters ) on his problematic pumps. I observe. I can tell about his grasp (understanding) of the problem by his available equipment…and his dexterity handling his equipment and managing his men.

I find I am able to analyze most “pump” problems:
1. by observing, listening and talking with the operators and mechanics.

After analyzing the probable pump problem, I find I am able to resolve most pump problems with:
2. a set of pressure gauges (for the suction and discharge nozzles of the pump),
3. a clip-on flowmeter,
4. the pump performance curve, and sometimes
5 an amp meter.

Often the problem is not in the pump, but in the equipment leading to, or away from, the pump.

Last June, a chemical plant in the Caribbean contracted me regarding a critical pump. I was flown 1st class to the chemical plant 3 hours out of Miami, and put into a 5-star tourist hotel suite. The critical pump was vibrating. The bearings were overheating. The pump had been eating seals and bearings for 10-months.

The vibration technician, with his $60-k analyzer, couldn’t isolate and identify the vibrations. The pumped liquid was not really hot. But the axial roller bearing was hot, and the pump was quite noisy. The engineer wanted my opinion on a better mechanical seal and some synthetic lubricant.

I ordered to install 2 pressure gauges on the suction piping. One gauge was installed onto the exit nozzle of the tank being drained by the pump. The other gauge was installed onto the pump suction nozzle. We started the pump and observed the gauges.

The reading on the gauge at the tank exit nozzle didn’t match the elevation in the tank. The differential pressure was inadequate on the two gauges leading into the pump. We drained the tank.

A hard hat was lodged into the exit nozzle of the tank, preventing the free flow of fluid through the pipe leading to the pump.

We removed the hard hat, filled the tank, and started the pump. The pump vibrations and noise went away.
The hard hat had an ID number. The hat had been missing for a year. The hat had been checked-out to a young intern engineer last year who was cycling thru the Safety and Inspection Department. The intern had inspected the tank last year.

As he left the plant, the intern engineer told the guard he had left his hard hat in the cafeteria, or men’s bathroom.

The hard hat was never found, or turned-in to the guard shack.

Oh well!
Later,
Larry Bachus

This pump was plugging once a week and it – eventually – was found to have the incorrect impeller installed at the factory, which only was designed to pass 2” spheres.

Operators are key to good design and proper maintenance

The Design Engineer and Operators of utilities need to meet often during the engineering phase of a project.

Who is the very best resource for designs of new (or upgrades of old) water/wastewater systems?…of course, the answer is…it depends as to what is meant by “best resource” and at what point in the evolution of a project.

Recently, I was reading an article on pumping station design and the author – a very competent and seasoned engineer/designer – stated that the most crucial element in design can be the operator or operations personnel. How can this be? Well, the truth is that pumping systems are nearly always complex beyond their initial or preliminary needs. Frequently, there are field circumstances which are far beyond the vision or knowledge of the design engineer. And, the knowledge of the operations staff is always crucial to maintenance of pumping stations – both new and upgraded stations.

The author, further, went on to state that operations staff should be involved in at least 3 stages of design (minimum) and – where practical – might be an integral part of the design team at all stages of design.

Pumping Station designs are often complex and involve interrelated systems

Who is better qualified to determine the ability of local staff to do the required maintenance of the pumps and controls equipment? It certainly is not prudent judgment to design a pumping station and – after it is started up – find that no one within 300 miles can maintain the system. Controls, in particular, can be misapplied – even if they are the most efficient in design – if the owner cannot service the controls or cannot depend upon the local service people who normally service his system to do service on new controls.

Likewise, pumping systems can be shown – on paper – to be most efficient and, upon startup, it is found that the owner is not set up to service such pumps (for instance submersible pumps requiring large hoisting equipment). Of what value to the owner is a very sophisticated and efficient pump system if the system cannot be readily serviced locally? An example might be a submersible pumping station where State or local code may require sophisticated setup procedures for maintaining this equipment. In smaller utilities, in particular, it may be that the owner must call upon a neighboring utility or an expensive service provider any time any alarm system is activated. This is a very costly experience for this particular owner – while it may be a routine call or maintenance issue for another utility. “It depends.”

Pumps and Controls for water and wastewater are integrated 'machinery'

Thus, in any pumping system design, begin with a defined teaming relationship with the owner/operators of the installed equipment. And, involve them at crucial milestone meetings along the way. It is with this type of engagement that you can expect a reliable and readily maintained final system…not to mention the “buy in” by the operators who will be maintaining these vital elements in each utility. Good designs begin with the end in mind. And, the “end” is the day-to-day operations and maintenance so crucial to lowest life cycle cost of ownership.

Don Voigt, P.E., M.S.M.E.

don@equipintegration.com