Dwyer Instruments DS-300 Series Installation And Operating Instructions Download Page 1

Series DS-300 Flow Sensors 

are averaging pitot tubes

that provide accurate, convenient flow rate sensing. When
purchased with a Dwyer Capsuhelic

®

for liquid flow or

Magnehelic

®

for air flow, differential pressure gage of

appropriate range, the result is a flow-indicating system
delivered off the shelf at an economical price. Series DS-300
Flow Sensors are designed to be inserted in the pipeline
through a compression fitting and are furnished with
instrument shut-off valves on both pressure connections.
Valves are fitted with 1/8˝ female NPT connections.
Accessories include adapters with 1/4˝ SAE 45° flared ends
compatible with hoses supplied with the Model A-471
Portable Capsuhelic

®

kit. Standard valves are rated at 200°F

(93.3°C). Where valves are not required, they can be
omitted at reduced cost. Series DS-300 Flow Sensors are
available for pipe sizes from 1˝ to 10˝. 

INSPECTION 

Inspect sensor upon receipt of shipment to be certain it is
as ordered and not damaged. If damaged, contact carrier. 

INSTALLATION 
General -

The sensing ports of the flow sensor must be

correctly positioned for measurement accuracy. The
instrument connections on the sensor indicate correct
positioning. The side connection is for total or high pressure
and should be pointed upstream. The top connection is for
static or low pressure.

Location - 

The sensor should be installed in the flowing line

with as much straight run of pipe upstream as possible.  A
rule of thumb is to allow 10 - 15 pipe diameters upstream
and 5 downstream. The table below lists recommended up
and down piping.

PRESSURE AND TEMPERATURE

Maximum: 200 psig (13.78 bar) at 200°F (93.3°C).

Series DS-300 Flow Sensors

Installation and Operating Instructions Flow Calculations

Bulletin F-50

DWYER INSTRUMENTS, INC. 

Phone: 219/879-8000

www.dwyer-inst.com

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. 

Fax: 219/872-9057

e-mail: [email protected]

1-3/4 (44.45)

1-11/16 (42.86)

1-5/8 (41.27) TYP

1-15/16 (49.21)

LP

HP

1/4 MALE NPT

5/16 (7.94)

* Values shown are recommended spacing, in terms of internal diameter for normal industrial       

metering requirements. For laboratory or high accuracy work, add 25% to values.

**

Includes gate, globe, plug and other throttling valves that are only partially opened. If valve is to 

be fully open, use values for pipe size change. 

CONTROL VALVES SHOULD BE LOCATED 

AFTER THE FLOW SENSOR.

Upstream Condition

Downstream

Upstream 

Minimum Diameter of Straight Pipe

In-Plane

Out of Plane

Upstream and Downstream Dimensions in 

Terms of Internal Diameter of Pipe

*

One Elbow or Tee

Two 90° Bends in

Same Plane

Two 90° Bends in

Different Plane

Reducers or Expanders

All Valves** 

7

8

18

8

24

9

12

24

8

24

5

5

5

5

5

REVISEDBulletin F-50  7/8/04  8:04 AM  Page 1

1.800.868.7495

QualityInstruments-Direct

.ca

Summary of Contents for DS-300 Series

Page 1: ... pointed upstream The top connection is for static or low pressure Location The sensor should be installed in the flowing line with as much straight run of pipe upstream as possible A rule of thumb is to allow 10 15 pipe diameters upstream and 5 downstream The table below lists recommended up and down piping PRESSURE AND TEMPERATURE Maximum 200 psig 13 78 bar at 200 F 93 3 C Series DS 300 Flow Sen...

Page 2: ...6 to allow for thermal expansion 5 Tighten packing gland nut finger tight Then tighten nut with a wrench an additional 1 1 4 turns Be sure to hold the sensor body with a second wrench to prevent the sensor from turning INSTRUMENT CONNECTION Connect the slide pressure tap to the high pressure port of the Magnehelic air only or Capsuhelic gage or transmitting instrument and the top connection to the...

Page 3: ...e 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...

Page 4: ...ssure expressed in inches of water column Q Flow expressed in GPM SCFM or PPH as shown in equation K Flow coefficient See values tabulated on Pg 3 D Inside diameter of line size expressed in inches For square or rectangular ducts use D 4 x Height x Width π P Static Line pressure psia T Temperature in degrees Fahrenheit plus 460 Rankine p Density of medium in pounds per square foot Sf Sp Gr at flow...

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