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See You at the Station – NPSH

July 31, 2013/in Blog/by Mark Taylor

A Positive Story about Managing the Liquid Limit in a Waste Water Lift Station

Here is the good news about understanding the concept of, Net Positive Suction Head or NPSH. If you understand the theory of Bernoulli’s principle you probably do not need a basic overview of NPSH. The bad news is maybe you haven’t the foggiest idea of how this mathematical equation helps one determine the value of NPSH.

Photo Credit Wikipedia

After sometime spent on the internet I believe the best definition of NPSH:

“NPSH is used to denote the suction performance of a pump without regards of the system to which it is installed.”

Sounds simple enough, but it is not.

In all actuality submergence level of a pumps intake in relation to the surface of the water above creates a better picture of what we are attempting to define. Remember that the height of water produces head, or what is called pressure head. The distance of the pumps intake below the surface of the liquid gives us the basic concept of suction head.

With the basic understanding of NPSH you can better conceive of what is meant NPSHa or suction head available. As an installer of packaged waste water pump stations, NPSHa became easy for me to understand. I associated the dynamic of suction head available by thinking of the term available as synonymous with tools or means available. For example, nature supplies a means or tool for those of us concerned with suction head available in the form of our atmosphere. This important sphere (slightly more important as it supplies us with the oxygen we breathe) is an element in creating pressure head on the water’s surface and thus helping to create suction head available.

At sea level the atmosphere produces the same amount of pressure as a column of water approximately 30’ high. Hydraulic modeling is something that is usually beyond the capabilities of station builders. When it comes to a Basic simulation of how a pump in a waste water lift station performs in relation to NPSHa ,(net positive suction head available) the station supplier can run some basic empirical tests.

The applications engineer can put the pumps through some differing suction head conditions that would apply to the hydraulic performance of the pumps under differing liquid levels in the waste water station. The packaged waste water station designer, as a professional in the industry, has to be concerned with cavitation and should attain from the manufacturer the NPSHr (net positive suction head required). In any “run up” performance test on the pumping operation cavitation is a paramount concern. The potential for the temperature of the effluent in the waste water lift station to increase can affect the NPSHa.

It’s getting hot in here!

All liquids have a vapor pressure. Vapor pressure of a liquid is the transformation of a liquid to a gas. As the temperature of the liquid increases vapor pressure rises to the point of gas escaping in the form of bubbles or cavities in the liquid. These air pockets will collapse as they go from the low pressure vortex to the pressure stream. There is actually less NPSHr in the pumping of warmer water, but the challenge is to keep the fluid in its liquid form and warm water poses a challenge in this respect.

In closing:

There are many mathematical equations that analyze fluid flow dynamics problems where cavitation may occur. Math formulas are tools that give the pump technician the ability to check the actual field and environment conditions against known mathematical values. Computing all the variables that contribute to cavitation in the submersible sewage pump can be done by a wonderful program called excell. So, to keep a waste water lift station pump on the positive side of suction head and positively produce a pump station with a long MTBF, let’s not get negative.

See you at the Station- Lets make a Deal on a Pre-Fabricated Waste Water Pump Station

July 23, 2013/in Blog/by Mark Taylor

For sale one “Taylor Made pre-fabricated Waste Water pump station”

Play along with me on this blog as I attempt to create the analogy in the sale of a used pre-fabricated waste water Pump station to that of the actions a person might take in selling their automobile. It is a comparison that makes one think.

The public works manager or the asset manager should equate the regular maintenance of a pre-fabricated waste water pump station to its current “used” value along any point of its life cycle. I can’t think of any method that is better to show the current value of a used asset, than to put it up for sale.

So, here we go, are you ready for your first buyer?

Our interested party is a very sophisticated customer named John. John reads a lot of blogs, including “See you at the pump station” so he is really in the know. Now, our professional public works representative, who we will call Tom, is already a little rattled as he can’t find the “Pump Fax” report and he knows the buyer will want to see the work report on this 2007, Taylor Made prefabricated waste water pump station.

Alas, at the last moment the work order logs are located, and after a look our customer states that the reports are well formatted. Tom is quick to point out that the detail in the paper work specifications from the inspection and work order sheets as well as the OSHA required confined space signage is included in the purchase of the Taylor Made pre-fabricated waste water pump station”.

John knows the value of the “Pump fax” report but is giving no sign that this station is the one. Being a good asset manager of this imaginary city , John wonders “who would find their financial situation so dire to have to sell a sewage pump station?’”

Tom kicks his salesmanship 101 into gear, and mentions the energy efficient motors that come with the purchase of the “Taylor Made sewage pump station”. All the documents are there in the purchase order and its plain that Taylor Made Pump Stations, one of the few “Energy Trust” pump station builders with this designation, puts a great deal of emphasis in pumping optimization from both the hydraulic design as well as motor efficiency.

John finally nods in approval and almost shows his enthusiasm in this rare opportunity to purchase a low hour Top of The line Taylor Made pre-fabricated waste water pump station. Noticing this Tom moves on the performance aspect of the drives, which are likened to an Energy-Efficient “Gas Pedal” for electric motors, these speed controllers are of crucial importance in saving energy and reducing operating costs. The Taylor Made pre-fabricated waste water pump station, was specified for the pump supplier to utilize their controls and VFD’s for efficiency and single source responsibility.

The Taylor Made Pre-fabricated waste water station has both Brains & Beauty.

It was becoming plain to Tom that John was very impressed with all the features of the station as well as the maintenance records produced by the city. The PLC, with a Modbus connection provides all level control monitoring, status and alarm conditions notifications would be easy for his small public works department to learn and operate.

Now it is time to check under the hatch. John, had already done his homework on the 25HP submersible non-clog pumps and with under 1,000 hours on each pump he had little concern that the pumping ends and motors were of high quality and “top flight”(not to relate the pumps to the high quality brand of a similar sounding name, but excellent sewage pumps none the less).

The Taylor Made Pre-fabricated waste water station is also designed with easy clean in mind!

John, our buyer couldn’t help but notice the bright red tube standing out at the top of the station. He recognized the Patented EZZ-Klean device as the asset manager of his city he had them installed in two of his pre-fabricated waste water pump station. He is very aware of how they increase the MTBF (mean time before failure) of the pump station. John said, “I really haven’t seen anything with this station that I don’t like. I cannot take the concrete wet well with me, but if you will throw in the top and hatch we can put the lid on this deal”. Tom, thought it would be a month or two before this sewer line was converted to a gravity line and thus the station could be decommissioned and removed. So If you’ll excuse the pun, it was a “crappy” deal but both men came out smelling good.

Are you aware June is Save a Pump Month?

June 5, 2013/in Blog/by Mark Taylor

Because a pump is a terrible thing to waste…

Water and waste operators everywhere know the work horses of any municipal water or waste water system is the pump. That is why many officials in the public and private sector, as well as manufacturers have joined with Taylor Pump Stations in proclaiming June as save a pump month.

Save a pump month, How can I get involved?

So, what can we as professionals in the pump industry do to protect the pump motor and of course the pump end of this vital machine. We must be aware of the importance of taking care of some basic preventative maintenance tasks that when done routinely will prolong a pumps life. In the water and waste water industry it is primarily the roto-dynamic (centrifugal) pump that in many cases works around the clock 365 days a year. It is an amazing machine, one worthy of being at the top of the asset management priority ;public work directors-supervisors and field technicians are very aware of the long term benefits of a daily, weekly, monthly, quarterly, semi and annual inspection & maintenance schedule.

Experienced public works employees and private sector tradesman recognize that it its not just servicing the pump and motor itself but caring for the key equipment and varying components of pumping station that can truly extend a pumps MTBF (mean time before failure).

So what better way to “stay in the flow” and keep the flow going for this first annual save a pump month than by following the “Big 10” pump maintenance items.

Get a good base line of what is normal for your pumping operation. I.E. by using your eyes, ears, feel and smell you’ll begin to sense ahead of time any problems. It’s a little “zen” but it works.
It varies with the type of station but visually and operationally check the on/off level switches for proper operation, I.E. make sure floats are not “ragged up” or tangled.
Know enough of the alternating switch cycle that the lead/ leg pump operations is functioning.
Your pumps need the proper amount of ” juice” and on a 3ph motor that means the amount of voltage per the name plate on all 3 legs, with the allowable voltage variance of approximately 5%. Be sure to check the amperage that the motor is drawing, also available on the motors name plate. Given both inputs of voltage and amperage, the technician gets a good picture of the electric motors operating condition; which is key to the proper operation of the sewage pump station. Hazardous Voltages are present in motor control panels-don’t attempt to check voltage without proper training.
Manually insure the alarm is working by operating the switch or test button, the same goes for the alarm light.
Pay close attention i.e. be detailed in watching the read out of the PLC. Pump fault readouts-levels or any other alarm function is of no benefit unless you’re monitoring the readout with the knowledge of what constitutes the abnormal. I guess it goes without saying-you must be trained then use that training to understand the pumps vital signs.
Check the seals on the MCC doors. Insure the seal has not been compromised. A 4x NEMA enclosure is not a 4x seal rated if damage has occurred to the door latch or gasket.
Check for loose bolts and evident hardware deterioration-i.e. be a good housekeeper.
Activate valves-to insure a unfrozen condition. Grease when necessary-operate spring spring check valves-insure a good seal.
Kind of a catch all-pull submersible pumps periodically for a visual operational check. If at every maintenance interval a digital laser ray thermometer is used for temp check of all mechanical equipment it will create a baseline to note any spikes in heat, indicating a problem. Be constantly vigil of resonance or vibration. Finally clean the pump basin out on a semi annual basis. A word of caution here! A sewage pump station is one of OSHA’S highest level danger rated confined space environments. Do not enter under any circumstance without following the regulations. The EZZ-Klean™ device as manufactured by Taylor Made Pump Stations is an excellent way to clean a station without subjecting workers to the harmful environment below.

Each pump application will have its own set of plans. But use these maintenance ideas along with your own and make June and every month trouble free in your pumps life. Part of save a pump month is getting this knowledge out there, so pass the information along.

United States Patent Awarded to EZZ-Klean™ Method

April 4, 2013/in Blog/by Mark Taylor

The EZZ-Klean™ System by Taylor Made Pump Stations* now offers a safer and more economical system for cleaning sewage wet wells and pits, storm water Retention basins, digesters and grease interceptors.

Cleanliness, and safety for maintaining pump station wet wells, vaults digester sumps or just about any container for liquid waste is of prime importance. The DEQ, EPA and OSHA are especially sensitive to the implications of maintaining the highest quality of these factors and have stringent regulations that need to be considered in order for owners and workers to stay in compliance. In the past, the methods used to do the work needed to satisfy compliance with regulations were time consuming and cumbersome. The new method called “EZZ-Klean™” has been tested and proven. It has earned a US Patent to save time, costs, improve safety and remain in compliance.

The Patent for the EZZ-Klean™ method is based on utilizing the benefits of a sloped floor along with a wide mouth opening at or near the bottom the vault with a pipe that is accessible to a vacuum source from the top of the vault. This is what Mr. Garret Pallo, Principle Engineer with Civil West, liked about the EZZ-Klean™ System. Civil West recently designed the EZZ-Klean™ into a pump Station in Myrtle Point, Oregon. This created a more efficient and effective cleaning process. It can just be cleaned from above with a spray of water. This method was inspired when Taylor Made Pump Systems became aware of the time it was taking for workers to clean in confined spaces while also being in compliance with Oregon OSHA standards. These standards address particulars such as cleaning sludge, rocks, sticks and even bones which are known to cause pump impeller problems.

Along with being able to save time and costs, safety was another consideration that the engineers of EZZ-Klean™ wanted to make sure to address with their method. What theycome up with is a system that makes fall protection, ventilation equipment, retrieval tripods, spending a large amount of capital investment and labor hours obsolete. The EZZ-Klean™ method allows for ease of use and maintenance so owners and workers can save time and money while staying safe on the job. The EZZ Klean™ Method can be purchased through Oldecastle Concrete Store.

*About Taylor Made Pump Stations: An industry specialist in the construction and the installation of Prepackaged Pump Stations, Taylor Made Pump Stations installs and constructs branded, pre-packaged and owner designed Pump Stations. Fully licensed providers and installers, contractors, manufacturers, engineers, and SCADA personnel provide a full array of Pump Station services including lift station construction, consultation and installing pre-made and customized stations designed to fit the specific applications needed including automation options, low maintenance, on site bore drilling for field connections and more.

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