1. Diaphragm Meters1. Diaphragm Meters

Principles of OperationPrinciples of Operation

1. Diaphragm Meters1. Diaphragm Meters

1. Diaphragm Meters1. Diaphragm Meters

Residential MetersResidential Meters– AC-175AC-175

– AM-250AM-250

– AT-210/250AT-210/250

– AC-250AC-250

– AT-350AT-350

– AL-425AL-425

1. Diaphragm Meters1. Diaphragm Meters

1. Diaphragm Meters1. Diaphragm Meters

B109.2 (Over 500 CFH)B109.2 (Over 500 CFH) Flow Rates for each Class (CFH)Flow Rates for each Class (CFH)

– ClassClass MinimumMinimum MaximumMaximum» 500500 500500 899 899

» 900900 900 900 13991399

» 14001400 1400 1400 22992299

» 23002300 2300 2300 34993499

» 35003500 3500 3500 55995599

1. Diaphragm Meters1. Diaphragm Meters

CommercialCommercial– AC-630AC-630

– AL-800AL-800

– AL-1000AL-1000

1. Diaphragm Meters1. Diaphragm Meters

IndustrialIndustrial– AL-1400AL-1400

– AL-2300AL-2300

– AL-5000AL-5000

1. Diaphragm Meters1. Diaphragm Meters

Type Max.Pres ½” P 2” PAC-250 10 250 CFHAL-425 25 425 CFH 900 CFHAL-800 25 800 CFH 1700 CFHAL-1000 100 1000 CFH 2200 CFHAL-2300 100 2300 CFH 5000 CFHAL-5000 100 5000 CFH 11000 CFH

1. Diaphragm Meters

Capacity at Elevated Pressure Diaphragm meter capacities at elevated pressures must be de-rated to limit differential pressure to a maximum of 8” w.c.This practice of limiting differential pressure extends service life of valves and diaphragms.

1. Diaphragm Meters1. Diaphragm Meters

Capacity of diaphragm meter at elevated Capacity of diaphragm meter at elevated pressurepressure

QQrr = Q = Qi i x {( Px {( Pg g + P+ Pa a ) / P) / Pb b } } 3/43/4

1. Diaphragm Meters1. Diaphragm Meters

QQrr = Q = Qi i x {( Px {( Pg g + P+ Pa a ) / P) / Pb b } } 3/43/4

Where:Where:– QQrr = Rated Capacity at elevated pressures = Rated Capacity at elevated pressures

– QQii = Rated Capacity at 0.25 psig = Rated Capacity at 0.25 psig

– PPgg = Gage Pressure = Gage Pressure

– PPaa = Atmospheric Pressure = Atmospheric Pressure

– PPbb = Base Pressure = Base Pressure

1. Diaphragm Meters

Capacity at Elevated Pressure Example: What is the capacity of an AL-1400 diaphragm meter rated at 3000 SCFH at a 2” w.c. differential pressure when it is operating at 15 PSIG, an atmospheric pressure of 14.4 PSIA, and a base pressure of 14.73?

1. Diaphragm Meters

Capacity at Elevated PressureQr = Qi x {(PG+Pa)/Pb}

3/4

Qr = 3000 x {(15+14.4)/14.73}3/4

= 5000 SCFH

1. Diaphragm Meters1. Diaphragm Meters

Meter 2 psig 5 psig 10 psig 20 psig 100 psigAC-250 600 656 742AL-425 955 1038 1154 1367AC-630 1390 1515 1710 2010AL-800 1800 2100 2600 3200 7800

AL-1000 2300 2700 3400 4100 10100AL-1400 3200 3700 4600 5600 13800AL-2300 5400 6200 7700 9400 23000AL-5000 11900 13500 17000 20600 50500

1. Diaphragm Meters

Size of diaphragm meter operating at elevated pressure needed for a load. Qi = Qr / {(PG+Pa)/Pb}

3/4

Where:Qi = Rated Capacity at 0.25 psigQr = Load in SCFH PG = Gage PressurePa = Atmospheric PressurePb = Base Pressure

1. Diaphragm MetersMeter Sizing Based on Load Example:

Connected load = 3,500 scfhMeter pressure = 15 psigAtmospheric pressure = 14.4 psiaBase pressure = 14.73 psiaWhat size meter should be used?

1. Diaphragm Meter

Meter Sizing Based on Load Solution

Qi = Qr / {(PG+Pa)/Pb}3/4

= 3500/{(15+14.4)/14.73} 3/4 = 3500/ {1.9959} 3/4

= 3500/1.679= 2084 CFH

Use an AL-2300

1. Diaphragm Meter1. Diaphragm Meter

Meter 1/2” P@ 0.25 psig

2” P@ 0.25 psig

AC-250 250 565AL-425 425 898AC-630 630 1320AL-800 800 1700

AL-1000 1000 2200AL-1400 1400 3000AL-2300 2300 5000AL-5000 5000 11000

1. Diaphragm Meter1. Diaphragm Meter

MeterOperatingPressures

psigft3/rev

ProvingCircle

ft3

AC-250 5 1/9 1, 2AL-425 10, 25 1/5 1, 2AC-630 25 1/5 1, 2AL-800 20, 100 5/13 5, 10

AL-1000 25, 100 5/13 5, 10AL-1400 100 5/7 5, 10AL-2300 100 1 1/4 10, 100AL-5000 100 2 6/7 10, 100

1. Diaphragm Meter1. Diaphragm Meter

OptionsOptions– Pressure Compensating IndexPressure Compensating Index

1. Diaphragm Meter1. Diaphragm Meter

OptionsOptions– Temperature Temperature

CompensationCompensation

1. Diaphragm Meter1. Diaphragm Meter

OptionsOptions– AMR (Automatic AMR (Automatic

Meter Reading) Meter Reading) CompatibleCompatible

1. Diaphragm Meters1. Diaphragm Meters

AccuracyAccuracy

AL-1000 Diaphragm Meter Proof Curve

99.699.8

100.0100.2100.4

20 40 60 80 100

% of Capacity Flow Rate

% P

roo

f

1. Diaphragm Meters1. Diaphragm Meters

InstallationInstallation– Ship, store, and install Ship, store, and install

in upright positionin upright position

– Keep dirt and water Keep dirt and water outout

– Level Level ++ 1/4” 1/4”

– No undue stressNo undue stress

– Do not buryDo not bury

– Filter may be neededFilter may be needed

– Protect from damageProtect from damage

– Hand tighten swivels firstHand tighten swivels first

– Check for leaksCheck for leaks

– Slowly pressurizeSlowly pressurize

– Need for by-pass?Need for by-pass?

– Cathodic Protection Cathodic Protection considerationsconsiderations

1. Diaphragm Meters1. Diaphragm Meters

Factors that affect AccuracyFactors that affect Accuracy– Internal friction that increases differentialInternal friction that increases differential– Maintaining constant diaphragm Maintaining constant diaphragm

displacement over a range of operating displacement over a range of operating conditionsconditions

– External leaksExternal leaks– Internal leaksInternal leaks– WearWear