Dwyer DS-300 User Manual

Page 3

1-3/4 (44.45)

1-11/16 (42.86)

1-5/8 (41.27) TYP

1-15/16 (49.21)

1/4 MALE NPT

5/16 (7.94)

Using the appropriate differential pressure equation from Page 4 of this bulletin,calculate the differential pressure generated by
the sensor under normal operating conditions of the system. Check the chart below to determine if this value is within the
recommended operating range for the sensor. Note that the data in this chart is limited to standard conditions of air at 60°F
(15.6°C) and 14.7 psia static line pressure or water at 70°F (21.1°C). To determine recommended operating ranges of other
gases, liquids an/or operating conditions, consult factory.

Note: the column on the right side of the chart which defines velocity ranges to avoid. Continuous operation within these
ranges can result in damage to the flow sensor caused by excess vibration.

Flow Calculations and Charts
The following information contains tables and equations for
determining the differential pressure developed by the DS-
300 Flow Sensor for various flow rates of water, steam, air
or other gases in different pipe sizes.

This information can be used to prepare conversion charts
to translate the differential pressure readings being sensed
into the equivalent flow rate. When direct readout of flow is
required, use this information to calculate the full flow
differential pressure in order to specify the exact range of
Dwyer Magnehelic

or Capsuhelic

gage required. Special

ranges and calculations are available for these gages at
minimal extra cost. See bulletins A-30 and F-41 for
additional information on Magnehelic

and Capsuhelic

gages and DS-300 flow sensors.

For additional useful information on making flow
calculations, the following service is recommended: Crane
Valve Co. Technical Paper No. 410 “Flow of Fluids Through
Valves, Fittings and Pipe.” It is available from Crane Valve
Company, www.cranevalve.com.

Pipe Size

(Schedule 40)

1-1/4

1-1/2

2-1/2

Flow

Coefficient

“K”

0.52

0.58

0.64

0.62

0.67

0.71

0.67

0.70

Operating Ranges

Air @ 60°F & 14.7 psia

(D/P in. W.C.)

1.10 to 186

1.15 to 157

0.38 to 115

0.75 to 75

1.72 to 53

0.39 to 35

0.28 to 34

0.64 to 11

0.10 to 10

0.17 to 22

Operating Ranges

Water @ 70°F
(D/P in. W.C.)

4.00 to 675

4.18 to 568

1.36 to 417

2.72 to 271

6.22 to 193

1.43 to 127

1.02 to 123

2.31 to 40

0.37 to 37

0.60 to 79

Velocity Ranges

Not Recommended

(Feet per Second)

146 to 220

113 to 170

96 to 144

71 to 108

56 to 85

42 to 64

28 to 43

15 to 23

9.5 to 15

6.4 to 10

REVISEDBulletin F-50 7/8/04 8:04 AM Page 3