Booster System Basics Constant Speed Systems Pressure Booster
Booster System Basics: Constant Speed Systems
Pressure Booster Systems • • • WHAT IS A BOOSTER SYSTEM? BOOSTER SIZING REQUIREMENTS BOOSTER SYSTEM CONTROL ENERGY SAVING STRATEGIES DRAWDOWN TANKS
What is a Pressure Booster System? Pumps Control Panel Pressure Reducing Valves Headers, Piping and Isolation Valves, Pressure gauges, Solenoid Valve, Aquastat and copper tubing • All components mounted on a common base, tested and calibrated to site conditions
What you need to size a booster system? • Calculate the total flow requirement for the building – Number of Domestic Water Fixtures – Type of fixtures in the building – Type of building (residential, public, heavy use) – Special services
Total Flow = Total Fixture Units 100 GPM 50 HUNTERS CURVE 50 50 50 100 Fixture Units
What you need to size a booster system? • Calculate the total flow requirement for the building • Calculate the total pressure required for the building
Static Pressure • Based on the vertical boost required above the packaged system manifold • This component never varies Pstat
Fixture Pressure • Required pressure to operate fixture at farthest point from system. • Must overcome valve “start-up” pressure (i. e. 25 PSI min. required for flush valves to operate) • Never varies, this is always required as a minimum Pfix
Packaged System Losses • Systems are designed to have no more than 5 psi loss from suction manifold to discharge manifold • This must always be added into pressure calculations Ploss
Available Suction Pressure • Typically varies by about 10 -30 PSI • Can vary over time due to growth • Can also vary due to municipal re-structuring Pcity
Friction Losses • Usually calculated at 10% of total static requirement • Typically a very small boost pressure component • Can be larger as in the case of boost over a “campus-style” area or large low-rise building Pfric
Pressure Requirement E Fixture pressure D PRV Losses System Pressur Pump Boost Pressu C Static head B Friction Head A Supply pressure after water meter
Pressure Requirement Pump Boost Pressure (TDH) = Fixture Pressure + Package Losses + Static Head + Friction Head - Supply Pressure
Pressure Requirement Boost Pressure = System Pressure - Supply Pressure
Significance of System Flow in Booster Systems • Flow impacts system demand, not pressure - as demand increases, flow must increase at a constant output pressure • Flow governs pump actuation - therefore, flow should govern pump sequencing and actuation • System capacity matched to system flow requirement is most efficient and cost effective for domestic water pressure boosting
What are the most popular methods of booster pump control ? • Flow meter or flow switch – Instrument is in contact with corrosive water therefore requiring more maintenance
What are the most popular methods of booster pump control ? • Flow meter or flow switch • Pressure Switch – Requires non-overloading (NOL) motors – Requires a pressure drop across operating range – Can be unstable in operation resulting in “starving” the system of water (end of curve operation) – Mechanical switches increase possibility of failure
PRESSURE Effect of Suction Pressure (PSI) 50 Discharge Pressure 40 HP 30 20 Suction Pressure 10 0 50 100 150 200 250 300 350 GPM
Effect of Suction Pressure PRESSURE (PSI) 50 Discharge Pressure 40 HP 30 20 Suction Pressure 10 Suction Pressure 0 50 100 150 200 250 300 350 GPM
What are the most popular methods of booster pump control ? • Flow meter or flow switch • Pressure Switch • Current or k. W Sensing
Current Sensing • As the flow increases, so does the pump load • The motor must match the pump load • Current / Power draw for motors is proportional to the load (pump flow work)
Current - Flow Relationship PRESSURE (PSI) 50 40 PUMP CURVE HP 30 20 Motor Amps 10 0 50 100 150 200 250 300 350 GPM
Effect of Suction Pressure PRESSURE (PSI) 50 Discharge Pressure 40 HP 30 20 Motor Amps Suction Pressure 10 0 50 100 150 200 250 300 350 GPM
Effect of Suction Pressure PRESSURE (PSI) 50 Discharge Pressure 40 HP 30 Suction Pressure 20 10 Motor Amps 0 50 100 150 200 250 300 350 Suction Pressure GPM
Effects of Voltage Fluctuations on Motors % Change Full Load Amps % Voltage Change - 10 +11 -7 + 10
Current Sensing • Motors sized to match the power requirement • Current sensing allows flexible pump sizing to match the system load profile and energy requirement 33% - 67% capacity split • Duplex: • Triplex: 20% - 40% capacity split
Current Sensing • Duplex allows up to three steps of sequencing
Current Sensing • Triplex allows up to five steps of sequencing
Time 23 h 00 22 h 00 21 h 00 20 h 00 19 h 00 18 h 00 17 h 00 16 h 00 15 h 00 14 h 00 13 h 00 12 h 00 11 h 00 10 h 00 9 h 00 8 h 00 7 h 00 6 h 00 5 h 00 4 h 00 3 h 00 2 h 00 1 h 00 0 h 00 400 350 300 250 50 -50 Split 200 Actual Consumption 150 100 50 0 Flow Rate ( GPM) Typical Daily Demand Curve 500 450
Time 23 h 00 22 h 00 21 h 00 20 h 00 19 h 00 18 h 00 17 h 00 16 h 00 15 h 00 14 h 00 13 h 00 12 h 00 11 h 00 10 h 00 9 h 00 8 h 00 7 h 00 6 h 00 5 h 00 4 h 00 3 h 00 2 h 00 1 h 00 0 h 00 400 350 300 250 50 -50 Split 200 Actual Consumption 150 100 50 0 Flow Rate ( GPM) Duplex Booster - 50/50 Split Conventional Split 500 450
Duplex Booster - 33/67 Split 3 Step Control with No-flow shutdown 500 33 -67 Split 400 350 300 250 200 50 -50 Split Actual Consumption 150 100 50 Time 23 h 00 22 h 00 21 h 00 20 h 00 19 h 00 18 h 00 17 h 00 16 h 00 15 h 00 14 h 00 13 h 00 12 h 00 11 h 00 10 h 00 9 h 00 8 h 00 7 h 00 6 h 00 5 h 00 4 h 00 3 h 00 2 h 00 1 h 00 0 Flow Rate ( GPM) 450
Energy Consumption HP = GPM X Feet (Head) 3960 X (Pump Eff) x (Motor Eff) • Smaller pump at lower flows will be more efficient and consume less energy • Smaller motor is more efficient at lower loads
Time 23 h 00 22 h 00 21 h 00 20 h 00 19 h 00 50 -50 Split 18 h 00 17 h 00 16 h 00 15 h 00 14 h 00 13 h 00 12 h 00 11 h 00 10 h 00 9 h 00 8 h 00 7 h 00 6 h 00 5 h 00 4 h 00 3 h 00 2 h 00 1 h 00 0 h 00 33 -67% Energy Savings: 19% 12 10 8 6 Actual Consumption 33 -67 Split 4 2 0 Consumption (k. Whrs) Energy Savings Conventional vs. 33/67 Split 14
Energy Savings Conventional vs. 33/67 Split Total Energy Savings = Energy Cost = $0. 12 19% / k. Whr Savings per Year: $2, 280
What are the most popular methods of booster pump control ? • • Flow meter or flow switch Pressure Switch Current or k. W Sensing VFD with pressure transducers
No-Flow Shutdown and Tank Sizing When do you use it? Where should you install it? What size should it be?
Sizing and Selecting Drawdown Tank • Tanks are to be used in systems that do not have a continuous water demand • Tanks should NOT be sized according to booster size • Tanks should be sized to store 20 - 30 Gallons of water (2 - 3 GPM leak loads) • Tanks maintain pressure in piping system and supply small demands to allow pumps to be shutdown
Sizing and Selecting Drawdown Tank • Tank Storage Volume is governed by the Ideal Gas Law • Solving for storage volume gives: • Vstorage = Pdifferential x VTotal Tank (PTotal +PAtmosphere) • 3 factors must be considered
Tank Volume • Vstorage = Pdifferential x VTotal Tank (PTotal +PAtmosphere) • The bigger the tank, the better the storage
Differential Pressure • Tank storage Volume is proportional to the difference in the cut out and cut in pressures of the pumps • The larger the pressure differential the more water that will be stored in the tank • Vstorage = Pdifferential x VTotal Tank (PTotal +PAtmosphere)
Pressure Differential Calculation • Pdifferential = Pstop - Pstart • Pstop = Pressure at the tank when the system shuts down • For adjacent or package mounted tanks, this means the suction pressure plus the shutoff head of the pump • For remote mounted tanks, this is simply the normal system pressure at the location of the tank
Pressure Differential Calculation • Pdifferential = Pstop - Pstart • Pstart = Pressure at the tank when the system starts again down • For adjacent or package mounted tanks, this means the setting on the no flow (call on) pressure switch • For remote mounted tanks, this is simply the system pressure at the location of the tank when the call on pressure switch brings the system back on
Total Pressure • A lower Total Pressure will yield larger water storage for the same pressure differential • Lower Total Pressure allows for lower tank pressure rating • Vstorage = Pdifferential x VTotal Tank (Ptotal +PAtmosphere) • Lower tank pressure rating
Sizing and Selecting Drawdown Tank • All three of these factors must be considered in selecting the appropriate tank • Vstorage = Pdifferential x VTotal Tank (PTotal +PAtmosphere)
Where Should the Tank be Installed ? • Packaged Mounted – Tank water storage may be limited by tank size – Will require higher tank pressure rating – More Costly – Difficult to maneuver due to weight and may require building structural reinforcement.
Where Should the Tank be Installed ? • Adjacent Mounted – Tank is supplied as a loose component for connection on site – Tank is not mounted on skid with pumps – Contractor has freedom to locate tank in mechanical room – System is easier to maneuver
Where Should the Tank be Installed? • Remote Mounted – Roof mounting - Lowers Tank Total Pressure and Tank Pressure Rating Required – Allows for the use of smaller tanks for desired water storage – Contractor has flexibility locating and installing tank
Questions & Answers
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