HM 122 Fluid Friction Loss Measuring System

The results of a series of measurements areshown in Table 5.4.

E

-e

IrE(,.9.E

aizi(,

po

I

It

HM 122 FIuid Friction Loss Measuring System

IT

T

ITTt

Tt,

II,

,

T

The square increase of the pressure loss then intum becomes clear as the flow velocity increases.However, the pressure drop occurs more stronglywth the copper element than s the case wth thegalvanized steel element. The drop due to thegreater wall roughness is again more than com-pensated for by the arger cross secton and thelarger radius. ln contrast to the straight pipe sec-tion, less pressure losses occur with galvanizedsteel angles than is the case with the copperelements,

Eo

-

Eo

I,(,ilo

.9)

o 150EEEt 1oo

/

,/.

./ *.'./ ....' _1

-.{"---*"-.-r11----='-

400

v, trh

Fig. 5.5 Pressure drop at the angle combinaiions "1+2" and "2+3' (copper) and "9+10" and"10+1 1" (steel, galvanized) at dfterent flow rates

The flow directon also influences the pressuredrop when combined with angle elements. This isillustrated n Fig. 5.5. lf the flow is changed in theZ drection (combinaton "1+2" and "9+10"), a higherloss occurs than s the case wth a U deflection(combnation "2+3" and "10+1 1"). Ths effect can

5 Experjments c

HM 122 Fluid Friction Loss Measuring System

EEEEtEEEEEEEEEEEEF

-EEbb

EE

160

180

E(,pIEE(,

,go|,1=(,,I,9

140

O l2OEE 1oo

again be noticed more strongly with copper ele-ments than is the case wth galvanized steel, whe-re deviatons are apparent only at high flow rates.Figure 5.6 again shows the pressure drops of allinstalled elements with a fow rate of 700 l/h. Thetendency is the same wth the comparable anglesand bends made of copper ("1" to "5") and steel("9" to "13"). ln the case of the long bend ("5" and" 1 3"), greater pressure losses unexpectedly occu rthan is the case with normal bends and angles. lncertain crcumstances, this is attributable to theirpositon in the pipe section. The combination of two45'-angles ("6") results n similar values to thebend "4",, which can be expected due to the similargeometry.AIso, the hgh pressure drop at the cross sectionnarrowing "7" is apparent in Fig. 5.6 aganst whchthe widening "8" causes relatively lower losses.

l-=hwoovh,

0

Fig.5.6

5 Experimen'ts

Pressure drop at lhe elemenis "1" to "13" with a flow rate of 700 yh

36

HM 122 Fluid Friction Loss Measuring System

These losses are attributable to the pipe f rction.Theoretically, a pressure increase should evenoccur in the case of frictionjree flow. Both ele-ments are agan compared in Fig. 5.7.

Caleulation of the resistance coefficient

Q

E(5

elf)-

e(,

(,i-(,E

I

160

'140

o l2o:EE iooEta0

60

40

20

o300 400 500 600 700 800

v, t/h

Fig. 5.7 Pressure drop at the cross seclion narrowing "7" and the cross section wdening "8"

As an example, the resistance coefficient for avolumetric flow of V=700 l/h shoud be determinedwith the measured values for the pipe ange "2"and -pipe bend "4". Since no cross secton changeoccurs here, the smplified formula for ( can becalculated.

t

l

/

,/

-t'

ttI

5 Experiments 37

-

F-

h-

F-

EbF-

Ebl--EEeEEEEEf-

-EEEEE

E(,

IIE(5

(.5az.

=o

I.9

measuring glandsis used for 1.

Ths experment is intended to record the pressurelosses of the different pipeline fixtures. To do this,connect a double pressure manometer or differen-tial pressure sensorto the measurng glands of therelevant fixture, and carry out the measurement asoutlined in Section 2.5. The installation of fixtures

Pressure losses of pipeline fixtures

Method

HM 122 Fluid Friction Loss Measuring System

The pipe length between thereferred to the pipe center line

The following is obtained from the calouation va-riables:

I (2")= 1 .74e U")=o.zq

Both resistance coefficients are above the figuresquoted in the lterature (rough pipe knee for theangle: qrough=1 .27i in the case of a bend withFi/d=1 .375, (rough=o.4 is read off n the dagram).The devation is due to dirty transitions betweenthe pipes and the angle or bracket.

5.3

5.3.1

Element insidediameter

measuremenllength I

flowvelocity

B i, accordingto Blasus

hv

Brackel'2"

di=16 mm 175 mm 0.97 m/s 15412 0.028 98 mm

Bend "4" d'=16 mm '1 75 mm 0.97 m/s 15412 0.028 49 mm

Tab. 5 5 calculatjon variables for (

5 Experments Ja