Operation manual Pneumator
∙
Testo Industrial Services
∙
Version 1.4
∙
2019
∙
Page 17
9.
Operating mode VELO – Velocity measurement
Purpose:
The operating mode VELO (velocity measurement) is used for the measurement of
process velocity (e.g. in an air duct) with the help of a pitot tube.
Device function and schematic diagram:
In the operating mode VELO 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
velocity value, which is indicated on the display:
v = s * sqrt ( 2 * DeltaP / rho)
with
v = Velocity [m/s]
s = Pitot tube factor (without unit)
= 0.67 if a straight pitot tube
= 1.0 if Prandtl pitot tubes
rho = density [kg/m3]
DeltaP = Differential pressure [Pa]
sqrt = Square root
Programming:
o
Press MENU
o
Submenu „Mode“:
Press UP or DOWN, until VELO appears. Selecting with
OK.
o
Submenu „Unit“:
Define the favored velocity unit (button UP and DOWN,
confirm with OK). The maximum measurement range (is indicated in the VELO
display upper middle) is automatically converted.
o
Submenu „Settings“:
Here the submenu „“VELO-FLOW“ is relevant,
selecting with OK
o
Submenu „Density“:
Enter the media density (e.g.. air at 20°C: 1.20
kg/m3)
o
Submenu „Pitot tube“:
Enter the pitot tube factor
= 1.0 if straight pitot tube
= 0.67, if Prandtl pitot tube
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 are not relevant in
VELO, therefore they can remain unchanged.
Operation / application (VELO):
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 VELO and leaving the menu (MENU button), a
zero adjustment is automatically conducted, in case AUTO ZERO = ON. Thereafter
