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Brooks, Model 5850e – Brooks Instrument 5850E User Manual

Page 50

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4-18

Installation and Operation Manual

X-TMF-5850E-MFC-eng

Part Number: 541B102AAG

September, 2009

Section 4 Maitenance &
Troubleshooting

Brooks

®

Model 5850E

Q

GAS

x

Q

GAS

=

Desired flow rate of the gas (sccm)

P

NITROGEN

=

Density of Nitrogen at 70°F

P

GAS

=

Density of the gas (taken at customer temperature)

SG

GAS

=

Specific gravity of the gas (taken at customer

temperature)

Refer to Table 4-4 for specific gravities.

Example:

Q

gas

=

2,000 sccm

SG

gas

=

.269

SG

Nitrogen

SG

gas

Q

Nitrogen

=

SG

Nitrogen

=

2,000 x .269

=

538 sccm Nitrogen

In order to calculate the orifice conversion factor when using a gas mixture,
the following formula must be used:

Orifice

Conversion

Factor 1

P

1

Orifice

Conversion =

Factor

Mixture

+ P

2

Orifice

Conversion

Factor 2

100

Orifice

Conversion

Factor n

+ P

n

Where

P

1

=

percentage by volume of gas 1

P

2

=

percentage by volume of gas 2

P

n

=

percentage by volume of gas n

Example: Find the Nitrogen equivalent for 20 slpm of a 20% Helium and
80% Chlorine gas mixture.

Orifice
Conversion

=

20(.378)

+

80(1.598)

Factor

100

Mixture

Q

Nitrogen

=

Q

gas

(orifice conversion factor)

=

20 x 1.439

=

28.78 slpm Nitrogen

Q

GAS

x