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SIZING INSTRUCTIONS WELL-X-TROL® POTABLE WATER WELL TANK 1400 Division Road, West Warwick, RI 02893 T: 401.884.6300 F: 401.885.2567 www.amtrol.com Table 1. Series 420 & 447 Pressure Switch This handbook will discuss the basic sizing used for our larger Well-X-Trol®s such as WX-400, 420, 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 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. In these applications, full use of the maximum acceptance volume of the Well-X-Trol® is rarely required to meet job conditions. WX Model No. NON-CODE (NON-AS ME ) WX Model No. COD E (ASME) Total Volume (Gallons) Maximum Acceptance Volume (Gallons) Maximum Acceptance Factor (MAF) WX-401 WX-401-C 17.5 11.25 .65 WX–402 WX–402-C 25 11.25 .45 WX-403 WX-403-C 34 11.25 .33 WX-404 WX-404-C 68 34 .50 WX-405 WX-405-C 90 34 .39 WX-406 WX-406-C 110 34 .31 WX-407 WX-407-C 132 46 .35 WX-421 Not available 158 103 .65 WX-422 Not available 211 137 .65 WX-423 Not available 264 172 .65 WX-424 Not available 317 206 .65 WX-426 Not available 422 274 .65 WX-427 Not available 528 343 .65 WX-447 WX-447-C 53 34 .65 WX-448 WX-448-C 80 52 .65 WX-449 WX-449-C 106 69 .65 WX-450 WX-450-C 132 86 .65 WX-451 WX-451-C 158 102 .65 WX-452 WX-452-C 211 136 .65 WX-453 WX-453-C 264 170 .65 WX-454 WX-454-C 317 205 .65 WX-455 WX-455-C 370 239 .65 WX-456 WX-456-C 422 273 .65 WX-457 WX-457-C 528 341 .65 Based on 30 PS IG p re-charge (P1) Utilizing the Maximum Capacity of Full 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: A WX-423 with a total volume of (275) gallons will accept the following: Step One – Determine the Best Operating Pressure Range – Pump Cut-In (P2) to Pump Cut-Out (P3): GROUND LEVEL STATIC WATER LEVEL PUMPING LEVEL OR LIFT 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®, you can replace very large, cumbersome galvanized tanks. 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 240 FT. (In example) PUMP DEPTH WELL DEPTH 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 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®'s air cushion is sealed-in, there is no need for external air compressors or control devices. 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 (P2) and pump cut-out pressure (P3) that will give us the widest range. 700 600 500 T E 400 E F N I If we can use the maximum acceptance of the 420 D A E H 300 and 450 Series Well-X-Trol®, we can service much L A T larger jobs…with large pumps, without paying the O T penalty of higher installation and maintenance costs. 200 100 0 80 60 % EFF. Y C N E 40 I C I F F E 20 20 40 60 80 100 120 140 CAPACITY IN GPM -2- 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 its pressure rises from cut-off ((0) 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. 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 cut out pressure. For example: 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. 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® to a pressure (P1) equal to the minimum pressure required at the Well-X-Trol® location. In addition, we'll select a pump cut-in pressure (P2) 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. 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 (P2) of 30 PSIG on the pump switch, and we will pre-charge the Well-X Trol® to 30 PSIG (P1). 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. 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. -3- 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. Or pump cut-out pressure (P3) is 78 PSIG. 700 600 500 T E 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. Reading the curve, we can find the point that indi cates 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 E F N I D AE H L AT OT 400 300 200 100 0 80 600 60 500 EFF. % Y C N T E 40 I E 400 C 80 E I F F N F I E D A E H 300 60 20 L A % T EFF. O Y T C N E 40 200 I C I F 20 40 60 80 100 120 140 F E CAPACITY IN GPM 100 20 To Summarize: 0 We have used actual pump performance as shown 20 40 60 80 100 120 140 CAPACITY IN GPM 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® precharge pressure. (P1) Pump cut-in pressure (P2) of 30 PSIG. Pump cut-out pressure (P3) 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. -4- 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 mini mum 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: + 90 196 ÷ 2 = 98 Step Three: Calculate Acceptance Factor (AF) Remember our formula for calculating the acceptance factor (AF) for diaphragm tanks? Step Six: Select Well-X-Trol® Model that is Equal to or Greater Than "Tv". If ASME construction is not required, select from 420 series, Table 1. AF = 1 - 30 + 14.7 78 + 14.7 This example would be a WX-425. To Recap: 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 Five: Calculate Minimum Total We went through six steps to size a full acceptance Well-X-Trol® to gain maximum acceptance: Step One Determine pre-charge pressure (P1); pump cut-in pressure (P2) and pump cut-out pressure (P3) from pump curve of pump selected for system. Step Two Determine ESP Volume (Average GPM x run time) From pump curve: Step Three Determine AF: P2 + 14.7 Volume (Tv) of Full Acceptance Well-X-Trol® 1 - P3 + 14.7 Remember the formula: ESP Volume AF TV = Step Four Verify the calculated AF is less than or equal to the maximum acceptance factor for the Well-X Trol® required. 196 TV = .518 = 378 gallons Step Five Calculate total Well-X-Trol® Volume: ESP Volume AF TV - Step Six Select series 420 or 450 Well-X Trol® Model -5- NOTES -6- NOTES -7- 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 affiliates in the U.S. and elsewhere. All rights reserved. Part #: 9017-102 (04/11) MC# 10005