MKS 275420-1-GQ-T-00011, Instruction Manual

Page: 19 / 52

Series 275 Convectron Module with DeviceNet
Instruction Manual - 275502 19
When high voltage is present, all exposed conductors of a vacuum
system must be maintained at Earth ground.
3 Installation
•
Do not install the Mini-Convectron where it will be subject to corrosive gases such as mercury
vapor or fluorine which will attack the gold-plated Titanium sensor. Mini-Convectrons with the
Platinum sensor should not be used in corrosive environments.
•
For greatest accuracy and repeatability, the Mini-Convectron gauge tube should be located in a
stable room temperature environment.
•
All connections to the unit are to be made with shielded cable or cables. The shield or shields are to
be connected to the connector shell.
3.2.2 Environment
To minimize temperature effects, locate pressure gauges away from internal and external heat sources,
in an area where the ambient temperature is reasonably constant.
3.2.3 Location
Where you mount the gauge is critical to obtaining reliable pressure measurements. Long tubing or
other constrictions can cause large errors in pressure readings. If you mount the gauge near the
pump, the pressure in the gauge may be considerably lower than in the rest of the system. If you
place the gauge near a gas inlet or other source of contamination, the pressure in the gauge may be
much higher than in the rest of the system.
3.2.4 Grounding
Under certain conditions, dangerously high voltage can be conducted through a gas directly to an
ungrounded conductor almost as effectively as through a copper wire. The ability of an electric
current to flow through a gas under certain circumstances poses a serious risk. Do not touch the
exposed pins on any gauge installed on a vacuum system when high voltage is present.
The Convectron Gauge envelope may not be reliably grounded through its vacuum connection. For
safety, you must either:
•
Add a separate ground wire, or
•
Shield the envelope to prevent human contact. Ground the gauge envelope by using a metal hose
clamp on the gauge connected by a #12 AWG (minimum size) copper wire to the grounded
vacuum chamber.