7/30/2019 room pressure

1/13

Dipl. Ing. Andreas Trk

LABCONTROL

TROX GmbH Germany

7/30/2019 room pressure

2/13

Pressure regulation for different requirements

laboratories

operating rooms

clean rooms

quarantine ward

S3/S4 security laboratories

7/30/2019 room pressure

3/13

room pressure

room supplyroom exhaust

Normal room

Volume flow:1000 m/h 5%= 950 1050 m/h

Volume flow:1000 m/h 5%= 950 1050 m/h

room leakage 0.02 m(2 cm gap below one door)

room pressure about 1 Pa(by leakage volume flow 75 m/h)

no problem

7/30/2019 room pressure

4/13

room pressure

room supplyroom exhaust

Volume flow:1000 m/h 5%= 950 1050 m/h

Volume flow:1000 m/h 5%= 950 1050 m/h

room leakage 0.005 m(0,5 cm gap below one door)

room pressure about 20 Pa(by leakage volume flow 75 m/h)

You must use pressure control

Airtight room

7/30/2019 room pressure

5/13

room pressure

room supplyroom exhaust

Volume flow:1000 m/h 5%= 950 1050 m/h

Volume flow:1000 m/h 5%= 950 1050 m/h

room leakage 0.001 m(1 mm gap below one door)

room pressure 500 Pa!(by leakage volume flow 75 m/h)

Walls could be damaged

Very airtight room

7/30/2019 room pressure

6/13

p

=

*

*

2 A

V

According to Bernoulli:

If the area is nearly zero

The pressure will increase nearlyunlimited!

2

Even a lowest volume flowdifference will change the

room pressure

dramatically!

A = Roomleakage

= air density 1,2 kg/m3

= Volume flow difference

= geometric coefficient approx. 0,72

room pressure 500 Pa!

Physical Background

7/30/2019 room pressure

7/13

tightness

Leackagevolume flow

Pressurecontrol

=

**

2 A

Vp

2

Regulation triangle

7/30/2019 room pressure

8/13

0,02 m

0,01 m

0,005 m0,002 m0,001 m

0

5

10

15

20

25

30

35

40

45

50

55

0 20 40 60 80 100 120 140 160 180 200 220 240Leckagevolumenstrom / Leakagevolumelow [m/h]

Raumdruck/Roomp

ressure

[Pa]

approx. 1mm gap

=

**

2 AVp

2

approx. 1cm gap

Room leakage / room pressure

7/30/2019 room pressure

9/13

- 10 Pa- 25 Pa

- 15 Pa

- 15 Pa

- 10 PaP

Reference Pressure

The reference must be

stable / constant pressure

forbidden!!!

7/30/2019 room pressure

10/13

Attention

No pressure variation in reference room

No pressure variation in the ventilation system

In air tight rooms regard the hysteresis of the VAV regulator

every pressure room must be regulated to a reference room

the regulation quality dependents of all installed regulator inthe room, even the non pressure regulator

The pressure is every time a function of the leakage volumeflow

7/30/2019 room pressure

11/13

Controller

Pressure controlled room

Reference pressure

Room pressure / working with damper - only

Cheap solution

Damper will move to extreme positions (Open / Close)

Door switches can not be used in laboratories (Notallowed streamings are possible)

No fast reaction times possible

High pressure jumps after closing doors

7/30/2019 room pressure

12/13

Room pressure / volume flow cascade

Contr.Contr.

Master / Slave

Reference pressure

Pressure Controlled room Defined control areas

No extreme positions of the damper

No door switches needed

Fast control possible

Master / Slave situations possible

High transparency of data

7/30/2019 room pressure

13/13

Thank you for your interrest!

www.trox.de

Halle 6.2 Stand C14/C16