From the May-2017 issue
A Critical Role
Pumps and valves are key to system efficiency.
When it comes to moving water efficiently, pumps and valves play a critical role. Some efficiency concerns focus on the wastewater utility sector, where “the EPA state revolving funds are going to fixing failing existing sewers—not so much extending into new service areas as much as they have been, but now repairing the leaky infrastructure,” says George Vorsheim, director of marketing and communications for Environment One Corporation (E/One).
Part of efficiency centers on valve design, which is the most important concern when designing a control or backflow system, says Cal Hayes, general manager for Proco Products’ waterworks division.
“It has to be at the foremost of all engineers’ minds,” he adds. “If a valve fails, the costs affiliated can be astronomical when there would be a chance of extreme flooding of complete lift stations, sewage plants, industrial buildings, and the like.”
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Whether some technology is more efficient in applications than others “depends on if you can actually experience head loss,” says Tim Fallon, senior sales engineer for the Henry Pratt Company. “The best idea is to take a look at how fast of a flow rate you are going to have across that valve. The higher that flow velocity, the more head loss you’re going to be able to realize.”
Fallon references a plug valve that has a specific Cv, or flow efficiency. “Cv is defined as the flow rate across the valve at 1 psi of differential,” he says. “You start the flow across the valve. You have a pressure gauge on each side of the valve. As soon as you get up to a certain flow rate where you see a difference of upstream flow versus downstream flow as 1 psi, you record that flow rate and that’s your Cv.”
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The Cla-Val PC-22D Electronic Pump Control Panel
While pressure drop through the valve is usually what people think of when it comes to efficiency, “it really depends on the function of the valve,” says Mark Gimson, business development and marketing manager for Singer Valve.
“The common thought is a higher Cv value of a valve—how many gallons per minute can pass through a valve with a 1 psi pressure drop—must equal a higher efficiency, but that is misleading when it comes to control valves,” he adds.
“When you’re looking at valve design, you cannot create or destroy energy,” points out Fallon.
The company is a subsidiary of Mueller Water Products and manufactures flow control equipment for the municipal drinking water and wastewater sectors. Among its products are butterfly valves and flow control equipment for the processes that clean water in the water treatment plant.
“As long as water flows in a straight line, that’s about as efficient as you can get,” says Fallon. “As soon as it changes direction through an elbow, an outer branch of a T, or goes into a more narrow or larger area—such as from a 6-inch to 8-inch transition—you lose energy in the form of head loss.”
In designing a valve, the goal is to maintain the same constrictions that were present as the fluid enters and exits the valve, he adds.
“If you have a 10-inch valve, you want your mating pipe to be a 10-inch. You don’t want it to be 10 1/2 inches and you don’t want it to be 9 3/4 inches. You want it to be almost the exact same size as the mating piece of pipe so it doesn’t have to change direction. It’s worse going from a small to a large area than it is going from a large area to a small area. That’s already been proven in hydraulic handbooks.”
In a butterfly valve, it’s important to have a disk as thin as possible as to create the most minimal amount of obstruction or aperture ratio, Fallon points out, adding that the aperture ratio is the difference of what the disk contributes in terms of head loss versus the free-flowing area.
A gate valve is another design. “The gate comes out of the flow stream completely and allows unencumbered flow to occur,” says Fallon. “That’s a very efficient way, but it also has its drawbacks in that there are guide rails in the side of the body and depending on the orientation of the gate, they could foul up with debris or tuberculation. They’re used in fire protection because they offer a very minimal amount of head loss.”
The bottom-line for valve design engineers is that the pressure-retaining component needs to be the same size as the upstream and downstream pipe with the design having as little obstruction in the flow stream as possible, Fallon notes.
A particular valve might be more efficient than others depending on its intended use, notes Gimson.
“If it is for some form of throttling, then a globe-style design is certainly the best,” he says. “However, this style of valve has more head loss than a butterfly valve, so if it is a simple on/off operation, a butterfly valve would be more efficient. The issue with butterfly valves is that they do not throttle well.”
A valve has to be carefully reviewed to ensure that the product will be the best choice for an application, points out Hayes.
The media has to be examined for the specific gravity, which will then allow the designer to choose an aggressive and rugged valve or a valve that only needs to handle air or clean water, he adds.
From that point, pressures and temperatures can force different choices in valve selection, says Hayes, adding that Proco Products has designed rubber check valves which have been engineered to provide optimal performance for aggressive slurries such as sewage, pneumatically conveyed powders, and viscous chemicals.
Credit: PROCO PRODUCTS
A 24-inch nominal diameter ProFlex 730/NN designed to provide barrnacle and algae resistance on an ocean outfall pipe.
Water used for fire protection is a case in point for efficiency, notes Fallon. “The water main is filled with water and it’s pressurized because the water source comes from an elevated storage tank, so the height of that water is what defines how much pressure is behind that water to push it into your house or business,” notes Fallon.
When the water is not moving, the pressure gauge will read 50 psi and as soon as the water starts to move, that pressure gauge can start to drop in terms of pressure because there is friction loss in the pipe itself as the water runs through an elbow or through a T, he adds.
“Every time the water has to change direction, you lose energy in the form of head loss,” notes Fallon. “As it goes through a valve, if there is an obstruction in that valve—such as the opening reduces a little bit and goes back open again—that acts as a form of restriction and slows down the potential of that water to flow efficiently through that valve and down that pipe.”
Depending on the type of valve, that restriction can cause a pressure loss that will show up in a terminal velocity as it comes out of the fire hydrant or a valve.
Credit: PROCO PRODUCTS
A 68-inch diameter ProFlex 730 valve with an enlarged
cuff, designed to slip over a RCP, provides backflow
The design engineer endeavors to source the most effective and efficient valve available for the right amount of money so that head losses are minimal, says Fallon.
“When a piping engineer lays out pipe and has put in isolation valves throughout the system, he or she is doing that because if a section were to fail, it can be isolated and repaired,” says Fallon.
“Or a process piece like a pump can be isolated. Every one of these valves has an associated head loss to them and the engineer has to account for every single piece of pipe and fitting and valve to know the total head loss of the system so that the pump can be sized correctly.”
Ultimately, infrastructure costs are wrapped up in energy costs, Fallon points out.
“You can’t look at it from the point of view that you have a lot of infrastructure to pay for,” he says. “The largest account payable that a water treatment plant operator is going to realize is the electric company. You have to pump it up to a tower. You look at how much pumping energy you need so you can save as much money as possible. A prudent engineer would be looking at the most effective valve, such as a valve that doesn’t offer any impedance like a ball valve.”
A ball valve is a full port without obstructions, Fallon points out.
“It almost acts like a piece of pipe,” he says. “Another type that has a little bit of impedance in it would be a butterfly valve. A butterfly valve has a disk right in the middle of the flow stream and how thin that disk can be will contribute to a little bit of head loss and that is not as effective as a ball valve.”
Fallon points out there is a significant difference in the cost of the two valves, with a 20-inch butterfly valve costing about $400 and a 20-inch ball valve costing about $15,000.
“Oftentimes, we try to compare the cost of a very efficient valve like the ball valve to a butterfly as it relates to the amount of life that that valve will provide in 20 years,” he says. “You could almost pay for the difference in electrical bills between the butterfly and the ball valve.
Acknowledging that not every water utility can afford the best and most cost-effective technology, “we try to compare it between a capital expenditure when the plant is being built and an operating expenditure as the plant is running,” says Fallon.
With a difference in head loss between a butterfly valve and ball valve, and “all things being equal in the pump running time, the electrical costs per kilowatt hour and a design life of 20 years, a utility pays more for the butterfly valve than for the ball. But from a financial standpoint when a city agency is looking to afford a new water treatment plant or an expansion of an existing one, they get the money through bonds and can only afford so much.”
There are a number of choices on the market when it comes to valves and pumps. Proco has recently introduced the lightweight 790 valve, designed for easy installation and low head loss concerns.
“In most outfalls from a city, the engineering groups are concerned with which valve to install with very low head pressure to prevent upstream flooding back on city streets, airport runways, and municipal CSOs,” notes Hayes.
Gimson says Singer Valve’s signature technology is its rolling diaphragm design for the automatic control valve industry, the Singer S106-PR Single Rolling Diaphragm (SRD). It’s designed to address the challenges of water loss management and the need for precise pressure management through providing stability throughout a complete range of flows.
That includes low flows, which prompt traditional automatic control valves to “chatter” and vibrate, requiring a smaller bypass valve in the pressure-reducing stations. According to company data, the 6 inches/150 mm and 8 inches/200 mm S106-PG SRD design controls down to the lowest industry published flows with no hunting or seat
chatter. Those valves have been added to the SRD technology from 10 inches/250 mm up to 36 inches/900 mm.
By eliminating the seat chatter at low flows, the SRD avoids injecting small pressure pulses into the piping, which may increase leakage and losses as well as pipe bursts.
Cla-Val manufactures automatic control valves. A valve’s efficiency is derived through its design as well as the pilot system and its components, notes Phyllis Dretzka, marketing manager.
“The basic valve is without a pilot system and then you add various pilots and components to make it specific to an application,” she says. “Valves can be electronic or hydraulic. They can be controlled with pressure reducing, pressure relief, pressure sustaining, and with flow control. It could be pump control. It could be something that helps reduce or eliminate surge. There’s a surge anticipator. There also are valves that are used for water savings.”
Water utilities specify valves according to their goals. “They may need special materials—stainless steel or something that is corrosion-resistant,” says Dretzka. “They may have brackish water. They may have a lot of debris in the water, in which case they need special strainers. It can be a strainer that is part of a pilot system or a strainer that’s just upstream of the valve.”
There may be a need for metering to know the flow rate. The Cla-Val Model X144 is a vortex shedding insertion electronic flow meter designed to be retrofitted into a Cla-Val Automatic Control Valve to provide accurate flow-measurement data without the need to install a separate in-line meter.
Other concerns include cavitation. For that, Cla-Val’s KO anti-cavitation trim is designed to combat cavitation in valves that are required to undergo extreme pressure differentials and high-velocity flow conditions.
Credit: ENVIRONMENT ONE CORPORATION
Grinder pump stations are often installed outside the home,
with only the access lid visible.
The seat and disc guide is constructed of 316 stainless steel with dual interlocked sleeves containing cast radial slots deflecting internal flow to impinge upon itself, dissipating potential noise and cavitation damage.
The radial slots in the seat and disc guides are designed to lessen the possibility of fouling if small particles are present in the water. The anti-cavitation trim components can be retrofitted to existing valves.
Among Cla-Val’s offerings is the 90 Series Pressure Reducing/Pressure Regulating Valve (PRV).
“It automatically reduces higher inlet pressure to a steady lower downstream pressure regardless of the changing flow rate or varying inlet pressure,” notes Dretzka. “The valve is very accurate and it can hold pressure to a pre-determined limit. That’s important. The valve is designed as a diaphragm valve that reacts to the pilot in its command.”
Variations on the valve include models with a strainer, KO anti-cavitation trim, low-flow bypass, combination pressure reducing and sustaining, pressure reducing and solenoid shut-off, combination pressure reducing and surge control, and electronic pressure reducing.
Other technology: the Cla-Val PC-22D, which is suitable for deep well applications, booster pumps, and 60 Series and 131 Series electronic control valves. It is designed to prevent surges in the system when the pump starts or stops.
Consisting of a pre-wired electrical control panel, the Cla-Val PC-22D uses a programmable valve controller to sequence the pump and pump control valve during all operation modes.
The programmable valve controller, housed in a NEMA 4X-rated enclosure, provides protection to the pumping system from damage due to mechanical, hydraulic, or power failure.
The PC-22D offers all control features in the Cla-Val recommended wiring diagrams, plus alarms, automatic shutdown, and adjustable timers.
The Cla-Val VC-22D valve controller is designed to enable remote or local set-point control of electronic valves in a variety of fluid applications, including water treatment facilities or potable water distribution systems.
It also serves as an interface between a SCADA system and other devices installed on or around the valve, such as a flowmeter.
Among the valve applications (ValvApps) for which the controller is pre-loaded:
- Flow control plus magmeter or X144 e-FlowMeter feedback
- Level control using position, flow, or on/off control
- Level control plus magmeter
- Upstream or downstream pressure control
- Position control
- Metering, flow control, DP, or P1P2
- Electronic downstream pressure control and optimization
The Cla-Val VC-22D also can be customized with additional ValvApps to meet any operational requirement through R-Designer to customize with multiple proportional integral derivative functions, totalizers, metering functions, various alarms, control curves, numerous timers, or any advanced logic system requirement. The valve controller is IP-68 submersible.
The E/One sewer system is a pressure sewer system powered by E/One grinder pumps. A pressure sewer system uses small-diameter pipes and grinder pumps, which collects all of the wastewater from the home, grinds it into slurry, and pumps it to a larger sewer main or directly to a wastewater treatment plant.
In contrast to gravity sewer systems using large mains installed in deep trenches, pressure sewer pipes may be as small as 1 1/4-inches in diameter and follow the contour of the land, says Vorsheim.
They are typically used in areas where a conventional gravity sewer system cannot be installed due to unfavorable land conditions or costs. Gravity sewer systems are bedded along a continuous downward grade, often involving deep trenches and large lift stations.
The pressure sewer systems are used in communities to replace septic tanks, upgrade existing pressure sewer systems, or as an alternative to gravity sewer systems.
“The concept of a light touch on the land is very important for more communities, not just around the US, but around the world,” notes Vorsheim.
Vorsheim points to recent events in Florida where algae blooms turned Florida’s Treasure Coast into a green, slimy soup.
While there was a massive fish kill due to pollution attributed to fertilizer run-off, septic tanks have also been targeted for blame, he adds.
“More recently, there have been other findings, specifically by Dr. Brian Lapointe at Harbor Branch Oceanographic Institute at Florida Atlantic University. When they tag the contaminants in the Indian River Lagoon, they can be traced back not necessarily to agricultural operations, but to human waste and specifically septic tanks,” says Vorsheim.
Vorsheim says a 50/50 matching grant program introduced by Governor Rick Scott and slated to be taken up by Florida lawmakers “is going to require a significant amount of political will and cooperation because when you put a network sewer in, that means the whole community is going to get sewer and with individual septic tanks, everybody is on their own.
“There are more than 600,000 septic tanks in the watershed for the Indian River Lagoon. What we’re looking at in Florida is significant migration from septic tanks to network sewer. We’re providing that solution now for Monroe County (encompassing the Florida Keys) in the contentious Florida Keys Aqueduct Authority septic to sewer conversion that’s been going on for several years now.”
Newer pump technology has become more “intelligent,” Vorsheim notes. “Communications is the next big stage for communities around the world,” he says. “Grinder pumps for pressure sewers are like little miniature lift stations for each house. A municipal-run system usually has to wait for an alarm to be called in by the homeowner, whereas when they have these SCADA-controlled lift stations, they are in communication with their lift stations that are handling a couple hundred homes plus on their gravity systems that are feeding into these big lift stations.”
E/One offers a technology called iota OneBox that is designed to provide total remote command control and communications of individual grinder pumps to the utility through a computer or mobile devices that offers a view of what is happening on individual properties, says Vorsheim.
The technology can provide information on tank storage capacities, power failures, blockages, and faults, and offer real-time diagnostics for individual properties, streets, or whole networks, as well as trend analyses, report generation, peak flow demand determinations, and flow smoothing, and maximized efficiency of downstream infrastructure.
“They can geofence, they can get into peak flow shaving, especially during rain events,” he adds. “You can avoid ‘sunny day flooding’ as we’re seeing more and more of. It makes the utility more efficient and that much smarter.
“We offer more control now to a system. We can control each individual home’s output whereas right now gravity sewers can only shut down a lift station that controls 200 homes,” says Vorsheim. “We can geofence it if there’s a break or some type of other transgression. Someone may be piping in illegally to the system. They can see that now with the OneBox system.”
Not only is delivering water efficiently through pumps and valves critical, but so too is the efficient delivery of chemicals.
Blue-White Industries manufactures chemical metering pumps and flowmeters designed to enable precise fluid measuring and pumping for industrial and municipal water treatment markets.
“These products are designed to inject chemicals into water systems and measure fluid flow with extreme precision resulting in the most efficient use of chemical,” notes Bill McDowell, senior sales engineer for Blue-White Industries.
The company’s line-up includes a number of pumps, such as the ProSeries metering pumps, designed as a low velocity injection system to pump a wide range of the aggressive and viscous chemicals used in water and wastewater treatment.
The operator changes the pump tube assembly to the appropriate material for the chemical to be injected. The metering pump is available in three models for various feed rates and capabilities.
Chem-Pro diaphragm metering injector pumps are designed to meet the rigorous demands of municipal water and wastewater treatment applications. The pump handles high-pressure applications up to 175 psi.
The Chem-Pro M has a PVDF pump head with large, double-ball ceramic valves and a built-in priming and degassing valve. It features ports for external wiring, a remote start and stop function, feed rate resolution from 1% to 0.1%, and a rugged variable speed drive.
Blue-White Industries’ Chem-Feed engineered skid systems can be floor- or wall-mounted for easy operator access. Applications include: municipal water treatment, municipal wastewater treatment, chemical metering, chlorination fluoridation, potassium permanganate, alum, sodium bisulfite or bisulfate, hydrochloric acid, polymers, caustics, and flocculants.
The system includes a pressure switch option. Components include Plast-O-Matic ball valves, pressure relief valve, gauge guards, and metal-free check valves. A flow indicator provides a visual indication of chemical movement through the system. Vented ball valves protect the system from chemicals that off-gas, such as bleach. A self-filling calibration cylinder is another feature.
Blue-White Industries also provides Sonic-Pro hybrid ultrasonic flowmeters that can be used in Doppler or transit time operation modes and measure fluid flow in any fluid in which sound waves can travel.
Ultrasonic sound transducers are clamped to the outside of the pipe wall to enable the Sonic-Pro to measure flow in both clean and dirty fluids. The Sonic-Pro is suited for use in applications where harsh chemicals and other abrasive fluids are used.
The meter can be equipped with a communications package for PC remote access allowing for program editing and downloading of data logs. A relay package is available for process control and alarm functions.