Operation manual Pneumator
∙
Testo Industrial Services
∙
Version 1.4
∙
2019
∙
Page 20
10.
Operationg mode FLOW – volume flow measurement
Purpose:
The operating mode FLOW (volume flow measurement) is used for measurement of
process-volume flow (e.g. in an air duct) with the help of a pitot tube.
Device function and schematic diagram:
In the operating mode FLOW the pump is turned off. The internal reference pressure
sensor immediately measures the differential pressure value of the process. This
value directly relates to the volume flow value, which is indicated on the display:
V = s * A * sqrt ( 2 * DeltaP / rho)
with
V = volume flow [m3/s]
s = pitot tube pressure factor (without unit)
= 0.67 if a straight pitot tube
= 1.0 if Prandtl-pitot tube
A = cross sectional area [m
2
]
rho = density [kg/m
3
]
DeltaP = differential pressure [Pa]
sqrt = square root
Programming:
o
Press MENU
o
Submenu „Mode“:
Press UP or DOWN, until FLOW appears. Selecting with
OK.
o
Submenu „Unit“:
Define the favored volume flow unit (button UP and DOWN,
confirm with OK). The maximum measurement range (is indicated in the
FLOW display upper middle) is automatically converted.
o
Submenu „settings“:
Here the submenu „VELO-FLOW“ is relevant, selecting
with OK.
o
Submenu „density“:
Enter the density media (e.g.. air at 20°C: 1.20
kg/m
3
)
o
Submenu„pitot tube“:
Enter the pitot tube factor
= 1.0 if a straight pitot tube
= 0.67, if Prandtl-pitot tube
o
Submenu „Area“:
Enter the cross sectional area in the air duct [m2].
o
Submenu „Setting
Zero“:
Definition of automatic zero procedure
o
Auto zero = ON: right after leaving the menu, and then on a regular
basis the zero points gets adjusted
o
Interval: Time Distance in minutes between two zero adjustments
o
Remark: The submenus „range“ and „steps“ in the main menu are not relevant
in FLOW, therefore they can remain unchanged.
Operation / application (FLOW):
Connect the pitot tube pressure-tight to the equipment. The end of the pitot tube is
connected with the „Plus“-junction, the other pitot tube-junction with „Minus“.
After selecting the operating mode FLOW und leaving the Menu (MENU button), a
zero adjustment is automatically conducted, in case AUTO ZERO = ON. Thereafter
