VACUUBRAND VSP 3000 - Manual (Page 14)

page 14 of 18
Documents are only to be used and distributed completely and unchanged. It is strictly the users´ responsibility to check carefully
the validity of this document with respect to his product. Manual-no.: 999159 / 22/07/2014
Pressure transducer VSP 3000
Operation principle VSP 3000
The pressure transducer VSP 3000 relies on the fact that the thermal conductivity of the residual gas
in the vacuum chamber is a measure for the gas pressure. The thermal conductivity of gases is propor-
tional to the pressure within a certain range and is related to the molecular mass.
The thermal conductivity of gases and vapours varies with their molecular mass. Therefore the pressure
measurement is dependent on the gas type. The pressure transducer has been adjusted for air at the
factory.
☞
Pressure of gases with similar mass, such as O
2
or CO, can be read off directly within the uncertainty
of the measurement.
☞ With gases of lower or higher mass (H
2
, He, Ar, CO
2
) it is recommended to readjust the VSP 3000
using the gas to be measured.
General information on handling
The pressure transducer VSP 3000 which has been developed particularly for use in chemical laborato-
ries is a pressure sensor working in the fine vacuum range.
Allow the VSP 3000 a period of approx. 20 minutes to warm up and to meet its specifications. Even
in case of the controller or vacuum gauge being switched off, the VSP 3000 stays ready for operation.
To de-energize the pressure transducer, unplug either its VACUU•BUS line or the power supply of the
controller or vacuum gauge.
The interior of the pressure transducer is highly sensitive! Do not insert fingers or
tools into the measuring chamber.
Prior to operation
➨ Connect gauge head by means of the VACUU•BUS line to a controller CVC 3000 or to a vacuum
gauge DCP 3000.
➨
Connect the gauge head to the vacuum chamber by means of the small flange connection or a hose
connection. Avoid contamination (oil/oil mist) of the gauge head when generating the vacuum with an
oil-sealed vacuum pump.
☞ Do not mount the gauge head directly at the oil-sealed pump but close to the vacuum process. The
diameter of the vacuum lines should be as large as possible.
☞ Inside a vacuum system where evaporation occurs (e.g., rotary evaporator) the vacuum is not uni-
form (e.g., a condenser acts as pump or the vacuum in the pipeline is lower than in the system).
Therefore choose carefully the position where to connect the gauge head.
☞ Condensate and deposits at the gauge head falsify the measurement result.
☞ If residues occur or when working with aggressive or condensable substances, install a gas washing
bottle in front of the pressure gauge head.
☞
Mount the gauge head in such a position that condensate can not flow into it.
☞ If necessary, clean the pressure transducer.
Recommended orientation: Vertically with vacuum connection pointing downwards. If mounting the
VSP 3000 in any other orientation, a readjustment is recommended.
VACUU•BUS
Readout of the pressure transducer via VACUU•BUS line by he controller CVC 3000 or by the vac-
uum gauge DCP 3000 using VACUU•BUS protocol (see instructions for use of vacuum controllers
CVC 3000 of vacuum gauge DCP 3000). Maximum cable length inside buildings: 30m. Extension cable
VACUU•BUS 2m: order-no. 612552.
NOTICE