Amtrol WX-401, WELL-X-TROL 420 User Manual

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SIZING INSTRUCTIONS

1400 Division Road, West Warwick, RI 02893 T: 401.884.6300 F: 401.885.2567 www.amtrol.com

Series 420 & 447

This handbook will discuss the basic sizing used for our larger Well-X-Trol 440, and 450 series. This allows you to use the Well-

X-Trol

“principle of separation of air and water” on larger jobs that are beyond the typical residential range.

The Well-X-Trol

models we’ll be working with in

Pressure Switch

s such as WX-400, 420,

this handbook are listed in Table 1.

The design features of these larger models allow us to apply them more creatively than the smaller

residential models found in the Well-X-Trol

100,

200, and 250 series.

The Larger Well-X-Trol

s are Designed and Built for Maximum Acceptance on Each Operating Cycle

In the smaller residential Well-X-Trol

s, the design

is for basic intermittent use and for the usually found in residential applications. Standard pressure ranges of (20) PSIG (between pump cut-in and pump cut-out) are used.

WELL-X-TROL

POTABLE WATER WELL TANK

Table 1.

WX Model No.

NON-CODE

(NON-ASME)

WX-401 WX-401-C 17.5 11.2

WX–402 WX–402-C 25 11.2

WX-403 WX-403-C 34 11.2

WX-404 WX-404-C 68 34 .50

WX-405 WX-405-C 90 34 .39

WX-406 WX-406-C 1103

WX-407 WX-407-C 1324

WX-421

WX-422

WX-423

WX-424

WX-426

WX-427

WX-447 WX-447-C 53 34 .65

WX-448 WX-448-C 80 52 .65

WX-449 WX-449-C 1066

WX-450 WX-450-C 1328

WX-451 WX-451-C 158102 .65

WX-452 WX-452-C 211136 .65

WX-453 WX-453-C 264170 .65

WX-454 WX-454-C 317205 .65

WX-455 WX-455-C 370239 .65

WX-456 WX-456-C 422273 .65

WX-457 WX-457-C 528341 .65

Based on 30 PS IG pre-charge (P

WX Model

No.

CODE

(ASM E)

Not avai lable

Total

Volume

(Gallo ns)

158103 .65

211137 .65

264172 .65

317206 .65

422274 .65

528343 .65

Maximum

Acce ptance

Volume

(Gallo ns)

Maximum

Acce ptance

Factor

(MAF )

In these applications, full use of the maximum

acceptance volume of the Well-X-Trol

is rarely

required to meet job conditions.

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Utilizing the Maximum Capacity of Full

GROUND LEVEL

STATIC WATER

LEVEL

PUMPING LEVEL

OR LIFT

PUMP

DEPTH

WELL

DEPTH

240 FT.

(In example)

36"

84"

WX-423

1489 LBS.

275 GALS.

TOTAL VOLUME

48"

AIR COMPRESSOR

900 GALLON GALVANIZED TANK

168"

10,000 LBS. (WITH WATER)

Acceptance Well-X-Trol

s Series 400,

420, 440 and 450

When used with conventional pressure ranges, these Well-X-Trol models use only a fraction of their maximum capacity.

For Example:

Step One – Determine the Best Operating Pressure Range – Pump Cut-In (P2) to Pump Cut-Out (P3):

A WX-423 with a total volume of (275)

gallons will accept the following:

at 30/50 – (85) gallons or 30.9%

at 40/60 – (74) gallons or 26.7%

By using the maximum acceptance of series 420 and 450 Well-X-Trol cumbersome galvanized tanks.

, you can replace very large,

Let’s Compare:

A 900 gallon galvanized tank is (48″) in diameter; (168″) long, and weighs approximately (10,000) pounds when filled with water.

Aside from initial cost, the cost of rigging and handling a tank of that size; (providing adequate support and the cost of space required) significantly adds to the overall installation cost.

Requires Air Control

Since at the higher pressures, the galvanized tank will waterlog at an accelerated rate, some provision must be made to maintain the required air cushion. This means the cost of an air compressor or other means of recharging must be added to the installation.

On the Other Hand

The first thing we must do in sizing the bladder is to determine the best pressure range that will achieve maximum acceptance.

. We can be accurate by letting the pump tell us at which maximum range it will operate best.

If we look at the pump curve for the pump which is to be installed…we can easily determine the pump cut-in pressure (P

) and pump cut-out pressure (P3)

that will give us the widest range.

The WX-423 has a total volume of only (275) gallons; is only (36″) in diameter; and (84″) high. When filled with water (to the 65% maximum acceptance) it only weighs (1489) pounds.

It can be easily handled by two men, requires no support structures and occupies a fraction of the space of the galvanized tank. Since the Well-X-

Trol

external air compressors or control devices.

If we can use the maximum acceptance of the 420

’s air cushion is sealed-in, there is no need for

and 450 Series Well-X-Trol larger jobs…with large pumps, without paying the

, we can service much

penalty of higher installation and maintenance costs.

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700

600

500

400

300

TOTAL HEAD IN FEET

200

100

EFF.

EFFICIENCY %

20 40 60 80 100 120 140

CAPACITY IN GPM

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For example, if we look at a typical pump curve for a (15) HP – (85) GPM submersible pump – we can select a pump cut-in and cut-out point on the curve which will provide optimum pump operation.

The pump curve shows pump performance as

(0)

its pressure rises from cut-off (

head in test) to

maximum head in feet.

On this curve, for a (15) Hp (85) GPM pump we can see that at approximately (100) feet the pump stops pumping and will pump up to (660) feet of head.

What we want to determine is at which point on the curve do we want to have the pump cut-in, and at which point on the curve do we want it to cut-out.

The pump operates in its best efficiency range at the mid-range of the curve.

We must select a minimum pressure at the Well-

X-Trol

location that will insure enough pressure to keep water flow under pressure at the top of the system…overcoming both the static height and the resistance to flow through the piping.

We’ll do this by pre-charging the Well-X-Trol a pressure (P required at the Well-X-Trol we’ll select a pump cut-in pressure (P

) equal to the minimum pressure

location. In addition,

) which is

at the same pressure to start the pump whenever system pressure drops to this point.

We’ll assume that a minimum system pressure

at the Well-X-Trol

location of (30) PSIG. This pressure will be adequate to insure system pressurization to overcome elevation and friction loss and provide adequate pressure at the fixture.

The cut-in point can’t be too low on the curve, as this would cause inefficient operation. We should choose a point just before the curve drops off rapidly…and at a point still within the best efficiency range (60% to 80%).

The pump curve for the pump selected indicates the total pressure range of the pump or its dynamic head measured in feet of head.

The pump must have enough head, or pressure differential to:

Bring water from the level of the well to the well head at the surface of the ground.

Provide head capacity to pressurize system piping to overcome elevation (static height) and friction (friction loss) and deliver required pressure.

Since the Well-X-Trol

will control the pump operation throughout system pressurization, we must select our pump cut-in pressure and pump cutout pressure.

For example:

To find this pump cut-in point on the pump curve, we’ll have to convert (30) PSIG to feet of head.

To convert PSIG to feet of head, we must multiply PSIG by (2.31).

30 PSIG x 2.31 = 69.3 or 70 feet of head

To locate this point on the pump curve, we must add 70 feet of head…the pump head required to pressurize the system to 30 PSIG…to the feet of head required to lift the water to the surface:

Minimum System Pressure = 70 Ft. of Head Plus Lift = 240 Ft. of Head

* Pump cut-in point on curve = 310 Ft. of Head

We have selected the point on the curve which will be the pump cut-in setting (P

) of 30 PSIG on the

pump switch, and we will pre-charge the Well-X-

to 30 PSIG (P1).

Trol

Now we will select the maximum pump cut-out point on the curve which will allow the widest possible pressure range without impairing pump performance and efficiency.

In a well with water level (240) feet down in the well, system pressurization by pump will be shown on the pump curve at some point above the intersection of the line indicating (240) feet of head.

In other words, at (240) feet of head we can assume that the pump will have brought water from the pumping level of the well to the surface and pressure in the system piping will be (0) PSIG.

We now must select a pressure range (min. to max.) to establish pressurized delivery of water to the system and that we overcome elevation (static height) and friction loss of the piping.

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We will do this by moving up the curve to find a point that:

Is just before the curve begins to “flatten” out

And is still within the upper limits of best

efficiency range of the pump

In this example, that point would be at the intersection on the curve of the horizontal line indicating (410) or (420) feet of head… let’s say (420) feet.

This is the point on the curve which will be the maximum pump cut-out for this particular pump.

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Subtracting the feet of head required for lift (240′) we can convert this point to PSIG:

Maximum pump cut-out = 420 feet Less lift = 240 feet

Maximum pressure = 180 feet

To convert feet of head to PSIG, we divide by (2.31) (there is (2.31) feet of head for each PSI): 180 ÷ 2.31 = 77.9 or 78 PSIG.

Even though the pump may be rated as a (85) GPM pump (as in our example) the actual capacity in GPM will vary as the pump operates throughout its pressure range from pump cut-in (30 PSIG) and pump cut-out (78 PSIG).

So, we’ll go back to our curve and determine what capacity in GPM the pump will deliver at its cut-in point, and what capacity in GPM it will deliver at its pump cut-out point. Then, we’ll average these two capacities by adding them together and dividing by two.

Or pump cut-out pressure (P3) is 78 PSIG.

700

600

500

400

300

TOTAL HEAD IN FEET

200

100

EFF.

20 40 60 80 100 120 140

CAPACITY IN GPM

EFFICIENCY %

To Summarize:

We have used actual pump performance as shown on the pump curve for the pump selected, to complete step one in utilizing maximum capacity of the full

acceptance Well-X-Trol

models, Series 420 and

450.

In this step we have determined:

System minimum pressure of 30 PSIG. To establish the Well-X-Trol

) Pump cut-in pressure (P2) of 30 PSIG.

Pump cut-out pressure (P

precharge pressure.

) of 78 PSIG.

Step Two – Determine, ESP volume required to control pump cycling. Determine average capacity in GPM:

With larger pumps, capacity, or flow of the pump will vary depending upon the pressure or feet of head at which it is operating.

Reading the curve, we can find the point that indicates pump cut-in. We already know that this is:

30 PSIG x 2.31 = 70 Ft. of Head Plus “Lift” = 240 Ft. of Head

Point on Curve = 310 Ft. of Head

700

600

500

400

300

TOTAL HEAD IN FEET

200

100

EFF.

20 40 60 80 100 120 140

CAPACITY IN GPM

Reading down to capacity we can determine that, at (310) feet of head, the pump will deliver (106) GPM.

We then read the curve to determine the capacity at pump cut-out:

78 PSIG x 2.31 = 180 Ft. of Head Plus “Lift” = 240 Ft. of Head

Point on Curve = 420 Ft. of Head

Capacity at (420) Feet of Head = 90 GPM

Determine ESP Volume:

Being a large pump, we will want to have a minimum run time of at least (2) minutes on the pump:

Average Capacity Average Capacity

at P2: 106 98 GPM x 2 = 196 ESP Volume

at P3: + 90

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196 ÷ 2 = 98

EFFICIENCY %

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Step Three: Calculate Acceptance Factor (AF)

Remember our formula for calculating the acceptance factor (AF) for diaphragm tanks?

30 + 14.7

AF = 1 -

78 + 14.7

AF = .518

Step Four: Maximum Acceptance Factor Verification

After calculating the acceptance factor (AF), we must compare the value to the maximum acceptance factors shown in Table 1. In the case of our example, an AF of 0.518 is less than the maximum acceptance factor of all WX-420 + WX-450 series models. Therefore, either series can be used.

Step Six: Select Well-X-Trol® Model that is Equal to or Greater Than “T

If ASME construction is not required, select from 420 series, Table 1.

This example would be a WX-425.

To Recap:

We went through six steps to size a full acceptance

Well-X-Trol

Step One Determine pre-charge pressure

Step Two Determine ESP Volume (Average

Step Three Determine AF:

to gain maximum acceptance:

); pump cut-in pressure (P2) and

pump cut-out pressure (P pump curve of pump selected for system.

GPM x run time) From pump curve:

”.

) from

Step Five: Calculate Minimum Total Volume (T Well-X-Trol

Remember the formula:

) of Full Acceptance

ESP Volume

TV =

196

TV =

= 378 gallons

.518

+ 14.7

1 -

+ 14.7

Step Four Verify the calculated AF is less

than or equal to the maximum acceptance factor for the Well-X-

required.

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Step Five Calculate total Well-X-Trol

Volume:

ESP Volume

TV -

Step Six Select series 420 or 450 Well-X-

Model

Trol

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NOTES

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NOTES

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1400 Division Road, West Warwick, RI 02893 T: 401.884.6300 F: 401.885.2567 www.amtrol.com

AMTROL, AMTROL logo and WELL-X-TROL are registered trademarks of AMTROL Inc. and afliates

Part #: 9017-102 (04/11) MC# 10005