Water TechnologiestmPAX

Inside America’s water storage tanks there’s a revolution going on...

www.paxwater.com

WINNER AWWAPeoPle’s ChoiCe AwArd

2007

Learn more about our Innovative Mixing Technologies, call 1-866-PAX-MiXer (1-866-729-6493)

The PAX Mixer solved our thermal stratification problem and continues to maintain great water quality. 

-Water Quality Manager, Redwood City, CA

“”

• superior mixing performance

• Quick and easy installation

• Consistent water quality

• eliminate stratification and stagnation

• Minimize residual loss

• Prevent conditions favorable to nitrification

The PAX mixing impeller

Water TechnologiestmPAX

PAX Water Mixer - Product SpecificationThe PAX Water Mixer is a robust submersible system for complete mixing of water storage reservoirs up to 7 million gallons. Independent of fill cycle operations, PAX’s patented impeller technology eliminates stratification, uniformly distributes disinfectant residual, and prevents conditions favorable to nitrification. The mixer easily installs through a conventional hatch in less than three hours without taking the reservoir out of service.

www.paxwater.com

Power suPPly requirement

Customer suPPlied Power switCh 

motor tyPe 

rPm

nominal Power draw

FootPrint diameter

height

weight

wiring

Control Center

 motor housing

stand

motor seals

Feet

120 VAC, GFCI-protected, 15 Amp circuit

NEMA 3R, fused, safety disconnect switch

Water-filled, water-lubricated brushless DC motor

1200

320 Watts @ 1200 RPM

4’ 3” (1.3m)

4’ 0” (1.2m)

62 lbs (28.2 kg)

Stainless Steel NEMA 3R Enclosure

316 Stainless Steel, NSF/ANSI Standard 61 compliant

316 Stainless Steel, NSF/ANSI Standard 61 compliant

UL listed Type THW- Submersible Pump Cable, Heavy Duty Flat 14/3 w/ground

MAteriAls

side View toP View

4' 0" 4' 3"

MiXer sPeCifiCAtions

NBR, chlorine/chloramine-resistant, NSF/ANSI Standard 61 compliant

EPDM, chlorine/chloramine resistant, NSF/ANSI Standard 61 compliant

PAX Water Mixer Product Specification

Specifications subject to change without notice ©2008 PAX Water Technologies, Inc.

Doc 1101-7019-00, Revised: 19 February 2008

PAX Water Mixer - Product Specification

The PAX Water Mixer uses proprietary technology to completely mix drinking water storage tanks up to

7 million gallons in size. The mixer is a simple, submersible, and robust system that easily installs

through a conventional hatch and can be assembled by a diver in less than one hour. Installation can be

completed without taking the tank out of service.

Mixer Specifications

Power supply requirement: 120 VAC, GFCI-protected, 15 Amp circuit

Customer supplied power switch: NEMA 3R, fused, safety disconnect switch

Motor Type: Water-filled, water-lubricated brushless DC motor

RPM: 1200

Nominal power draw: 320 Watts @ 1200 RPM

Footprint diameter: 4’ 3” (1.3m)

Height: 4’ 0” (1.2m)

Weight: Mixer Assembly 62 lbs (28.2 kg)

Weight: Control Center 24 lbs (10.9 kg)

Material: Control Center Stainless Steel NEMA 3R Enclosure

Material: Stand 316 Stainless Steel, NSF/ANSI Standard 61 compliant

Material: Motor Housing 316 Stainless Steel, NSF/ANSI Standard 61 compliant

Material: Motor Seals NBR, chlorine/chloramine-resistant, NSF/ANSI Standard 61

compliant

Material: Feet EPDM, chlorine/chloramine resistant, NSF/ANSI Standard 61

compliant

Wiring: UL listed Type THW-Submersible Pump Cable, Heavy Duty Flat

14/3 with ground

Figure 1: Side and top views of mixer

PAX Water Mixer Product Specification

Specifications subject to change without notice ©2008 PAX Water Technologies, Inc.

Doc 1101-7019-00, Revised: 19 February 2008

Figure 2: Typical mixer application – mixer is centered in water tank

PAX Mixer Control Center Power Requirements:

120 VAC, GFCI-protected, 5mA trip, 15 Amp circuit located

within 75 ft of load

Safety Switch Requirements:

A NEMA 3R or better, Safety Disconnect Switch installed by

customer and located within 10 ft of the mixer control center

Standards, Environmental & Temperature Specifications:

Control Center Temperature Ranges:

Operating temperature*: -40°F to 115°F (-40°C to 46°C)

Storage temperature: -40°F to 155°F (-40°C to 70°C)

*outside ambient temperature

Figure 3: PAX Control Center (upper box) and example of Safety Disconnect Switch (lower box)

Motor Specifications:

Water-filled, water-lubricated, maintenance-free brushless DC motor, carbon/ceramic thrust bearing

construction, no electronics inside motor housing.

Warranty For the period of time beginning with shipment to Buyer and ending on the time periods listed below, the

Product is warranted to be substantially free from defects in material and workmanship and to conform to

Seller’s specifications applicable to the Product –

• Two (2) years on all supplied parts

• One (1) year labor on installations completed by PAX Water Technologies, Inc. or approved third

party installation contractors.

Warranty does not cover damage due to: (i) lightning, flood or other acts of nature, or failure of or

inappropriate application of peripheral devices including lightning or surge protectors; (ii) negligence of

Buyer or any third party; (iii) vandalism or any other misuse or mistreatment of the product; or (iv)

installation by non-licensed contractor. Lightning protection is recommended in areas historically prone

to lightning AND is the responsibility of the Buyer for proper installation in accordance with local, state,

and national code requirements.

Product Data Sheet

Specifications subject to change ©2008 PAX Water Technologies, Inc.

Revised: 04 Sept 08

Temperature

Probes

Tank Hatch

PAX Tank Temperature Monitoring System

Example of the data logging temperature probe

Figure 1: Typical installation – probes hang underneath hatchway near tank wall

For more information, or to order, contact us at 1-866-PAX-Mixer or info@paxwater.com

Product Specifications

Fits Tanks 0 to 40 ft depth

Lead Time 2 weeks ARO

Logging Interval 10 minutes (adjustable 1 sec

to 18 hours)

Battery Life 5 years +

Wetted Materials Polypropylene, EPDM,

Stainless Steel 316

Accuracy +/- 0.2°C

Data Download

Either using reader onsite, or

send probes back to PAX for

analysis

Parts Included

3x Temperature Loggers,

1x Reader, 1x Software,

SS float, cable and clips

Temperature probes are a simple and effective

way to monitor temperature stratification in

tanks and reservoirs. Water temperature can be

used as an indicator of water quality and can

visually display the effects of low tank

turnover in your storage tanks. Steel tanks, in

particular those with sun exposure, often have

temperature stratification, which leads to

stagnant water and a decrease in disinfectant

residual and water quality.

Installing a temperature monitoring system

enables operators to quickly identify tanks that

have problematic stratification through

temperature profiling, saving the more

laborious need to profile tank chemistry for

stratified locations.

To install, simply clip the pre-configured cable

with data logging temperature probes onto any

support beam or fitting directly under the

hatch. Collect data for as long as you need,

and then it can be easily exported to MS Excel

or similar package using the USB reader for

analysis. As a service, probes can also be sent

back to PAX for analysis.

The PAX Tank Temperature Monitoring

System is adjustable to tank depth, and re-

usable from tank to tank.

PAX Water Technologies Case Study

©2008 PAX Water Technologies, Inc. Rev. 30oct08

Mixing Eliminates Stratification and Delivers Residual to Upper Layers in 1.5MG Standpipe

The Problem

Standpipes are one of the most problematic tank geometries to mix. Inlet velocities are

typically small in magnitude and horizontal in direction. The substantial majority of water in

the standpipe must remain in the tank to produce and maintain pressure head in the

distribution system, so there is often a hard limit (typically 70-90 percent of capacity) below

which the operators cannot draw. This takes away the default (yet energy and labor

intensive) method of mixing – i.e., the forced draw down and refilling of tanks.

The Spanaway Water Company (Spanaway, Washington) discovered the problem of low

turnover standpipes first-hand when an operator noticed a layer of condensation on the

outside of one of their standpipes. He surmised that the cold water inside the tank was

causing this condensation, but worried why the condensation was only visible 20 feet up the

side of the tank and did not cover its full height. An investigation of the temperature inside

the tank (see Figures 1 and 2) validated his theory – the tank had substantial thermal

stratification. The volume and velocity of the incoming water during a regular fill cycle was

not sufficient to overcome the thermal loading the tank received on its large, exposed surface

area – even in a state not known for its thermal extremes. Testing at the top of the tank

during normal operation showed almost zero chlorine residual.1 The warm, low residual

water remains trapped in the top of the tank until a period of high demand lowers the water

level enough to potentially allow this poor quality water (often with unpleasant taste,

temperature and odor – as well as possible high DBP2 levels) to enter the distribution system.

20 ft

40 ft

60 ft

80 ft

100 ft

120 ft

Thermocline

Inlet Outlet Figure 1: Photo showing the tank (left) and illustration of the thermocline inside the tank (right). Figure 2 below

shows the temperature data which was collected to establish the location and strength of the thermocline.

1 Grab samples of total chlorine were taken periodically at the top and bottom of this tank and although a residual of

0.7 – 0.8 mg/L was found in the bottom layer of the tank, the residual was 0.00 – 0.05 mg/L in the uppermost layers. 2 DBP – Disinfection By-Products, which include Trihalomethanes and Haloacetic Acids

PAX Water Technologies Case Study

©2008 PAX Water Technologies, Inc. Rev. 30oct08

Spanaway Temperature Probes - September Stratification

(final weeks before installation)

0

5

10

15

20

25

30

15-Aug 20-Aug 25-Aug 30-Aug 4-Sep 9-Sep 14-Sep 19-Sep 24-Sep

Wa

ter

Te

mp

[C

]

Float

80 ft

60 ft

40 ft

20 ft

~10C stratification persists through September

Copyright PAX Water Technologies - 1 Oct 08 Figure 2: Plot showing temperature stratification during August and September before mixer was installed at end of

September. Tank dimensions were 46 feet diameter and 127 ft tall. Water level was up to 120 ft during the time of

measurement.

Sudden loss of water quality in standpipes can also occur at the beginning of winter due to

“inversion.” Inversion occurs when the old, stagnant water at the top of the tank is no longer

warmed by the summer sun. Instead, the water is chilled by the cold winter air. This chilled,

colder water suddenly sinks to the bottom of the standpipe, which causes the standpipe to

rapidly invert. After inversion, the first water to be flushed directly into the distribution

system to supply customers is the oldest, lowest quality water from the top of the tank, while

the good water remains trapped at the top of the tank.

The Solution

Standpipes present a particular challenge for most mixing systems because of their height.

The PAX mixer has been demonstrated to restore water quality, reduce the need for on-site

chemical dosing, and improve reliability and homogeneity in ground storage tanks, but those

tanks tend to be wider than they are tall. Our analysis suggested that, despite the unfavorable

ratio of height to diameter of this standpipe, the PAX mixer would be able to penetrate an

established temperature gradient and completely circulate all 120 feet of the water column.

The installation of the PAX mixer took less than a day and required no crane or heavy

equipment. In contrast, older style mixing systems previously used in standpipes required

impractical 120-foot-long draft-tubes or tree-like piping structures built into the tank and a

long and expensive construction and installation process. These processes also required

draining the tank, welding, and recoating the inside surface. For the PAX mixer, the only

preparation was that the reservoir water level was lowered to 100 feet and isolated until

divers could complete the installation. The customer saw an immediate benefit.

Figure 3 shows the final days of stratification before the mixer was activated, and the

impressive results immediately following. Approximately every hour another vertical foot of

the stratified water column was blended with the cool, fresh, chlorine residual-rich water.

After seven days the entire water column was completely blended and the temperature of the

upper layer had fallen from 19°C (~66°F) down to below 16°C (61°F). Over the next several

weeks the average temperature of the reservoir dropped even further as new water was added.

The reduction in temperature allows the residual to last longer in the upper layers and lowers

PAX Water Technologies Case Study

©2008 PAX Water Technologies, Inc. Rev. 30oct08

the rates of reaction and DBP formation. Grab samples taken after one week of mixer

operation showed a dramatic increase in residual at the top of the tank: from 0.00 mg/L to

0.31 mg/L.

Spanaway Water Temperature data -

1.5MG, 46 ft x 127 ft tall standpipe

10

12

14

16

18

20

22

22-Sep 24-Sep 26-Sep 28-Sep 30-Sep 2-Oct 4-Oct 6-Oct 8-Oct 10-Oct

Wa

ter

Te

mp

[C

]

Float

80 ft

70 ft

60 ft

50 ft

40 ft

30 ft

20 ft

Mixer On

~60 hours to blend up to 80 ft depth

~24 hours to blend first 50 ft of water

Copyright PAX Water Technologies - 1 Oct 08

~155 hours to blend entire tank

Thermoclines still persist

Mixer Off

20 ft of cold water is

added to the tank here

Figure 3: Temperature probes at intervals in the standpipe show the mixer steadily overcoming the thermal

stratification in the tank.

With the active mixing provided by the PAX mixer, water quality throughout the tank has

been improved and the entire volume of water is now available for regular or emergency use.

There is no chance of an inversion while the mixer is operating in the tank. The reliability

and quality of Spanaway’s distribution system has been significantly improved by this simple

infrastructure upgrade, and minimal interruption of tank use was required. The Water

Programs Manager from Spanaway, Tim Tayne, describes the implications of the PAX

Mixing system in this way: “Consistency in the quality of water provided is the key to

customer satisfaction. This also ensures the drinking water always meets the drinking water

standards, even during high demand such as fighting fires or abnormally hot weather. The

volume of water in this reservoir with high water quality went from 0.25 million gallons

(MG) to almost 1.5 MG by installing the PAX mixer. We will be evaluating our other

reservoirs in the near future.”

Conclusion

With this breakthrough case study, PAX Water Technologies has proven that this innovative

technology (which has already proven successful in rectangular and circular ground storage

tanks) can now offer a solution for utilities seeking to improve water quality and reliability in

standpipes.

The PAX mixer is an active mixing solution that completely eliminates stratification on a

continual basis and does not rely on operator-adjusted drain or fill cycles. This continual

operation and independence from the pressure in the system makes the PAX mixer well-

suited for standpipe owners who often find themselves constrained in how much they can

drain and fill those tanks. Consistency, stability, and reliability of the distribution system are

enhanced by the PAX mixer.