Danfoss RAV Operating guide

Instructions

RAV - Installation for sensors

082R9106

082R9106

31 2

The main purpose of these
instructions for RAV group of
products is explaining how to make
and assure the correct installation of
the products in order to avoid
corrosion effect which could later on
cause complete malfunction of the
products.

We have experienced that main
corrosion effect is caused by so
called “galvanic” type of corrosion.
This type of galvanic corrosion is
caused by metal contact between
sensor’s housing and other metal
(e.g. inner wall or plate of heat
exchanger) in the presence of water.
Metal contact between sensor’s
housing and other metal causes
galvanic cell, which is a “perfect
condition” for previously mentioned
corrosion (especially when we have
a contact of two different metals).
Final effect of corrosion is “broken
housing” and lost charge (gas).
When charge is partly or completely
gone, product is not able to provide
its specified performance.

Water flow and resulting vibrations in
the system can result in so called
hammering of the sensor against
adjacent metals, which even
mechanically accelerates the whole
corrosion phenomena.

Please consider the following
recommendation supported by
relevant figures before you make
final installation of RAV products.

! Install sensor part as shown on

figure 1 in order to assure at least
5 mm distance between sensor
housing made of brass and other
metal parts.

! Consider adequate distance over

the whole side length and end part
of the sensor (figure 1).

! Assure that sensor is properly

fixed; larger dimension of capillary
tube has to be fixed with stuffing
box (2 washers with rubber gasket
in between, tightened with screw),
(figure 1).

! By installation shown on figure 1

you also assure the optimal arm
(distance between stuffing box
where sensor is fixed and end part
of the sensors inserted in the
media in heat exchanger or boiler)
which will reduce the risk of
vibrations which could cause a
metal contact.

! Please avoid installation which is

shown on figure 2 (thinner
diameter of capillary tube fits in
stuffing box, longer arm etc.).

! If you can not avoid or at least you

assume the possibility of metal
contact, than you have to use
a protecting pocket (sleeve) made
of stainless steel (figure 3).
By using this standard type of
accessory you will be faced with
longer response time of RAV’s
performance due to slower heat
transition.

7369186-0 SIBC R&D VI.52.B2.02 © Danfoss 8/00