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Technical Note
TruStability
®
Pressure Sensor Liquid Media Compatibility
and Guidelines
Sensing and Control
BACKGROUND
TruStability
®
Pressure Sensors (HSC Series High Accuracy
and SSC Series Standard Accuracy) have an available
option that extends performance from non-corrosive, non-
ionic gases to non-corrosive, non-ionic liquids and
condensing humidity on the primary pressure port (Port 1).
The information in this Technical Note is intended to assist
end users in understanding the performance of this “liquid
media” option.
When using pressure sensors across a variety of liquid
media, it is necessary to ensure that the sensor is able to
operate with the desired liquid without adverse effects. To
ensure compatibility, it is important to consider all the
materials in the sensor with which the liquid will come into
contact.
Customers using the liquid media option should review the
product data sheets to understand the materials in the liquid
media’s path. Ultimately, it is up to the customer to
determine if the sensor is compatible with the liquid media
and is right for the application. Honeywell can assist in this
effort, utilizing our existing application knowledge and testing
experience.
PRESSURE PORT DESCRIPTION
TruStability
®
Pressure Sensors have two pressure ports,
labeled Port 1 and Port 2, on the dimensional drawings in
the product data sheets. Port 1 is the primary pressure port
and Port 2 is the reference pressure port (see Figure 1).
Figure 1. SIP AN Port Configuration Dimensional Drawing
0,25
[0.010]
2,54 TYP.
[0.100]
PORT 1
1 2 3 4
10,0
[0.39]
4.93 DIA.
[0.194]
10,0
[0.39]
13,75
[0.541]
15,2
[0.60]
PORT 2
4X 0,51
[0.020]
PRESSURE PORT COMPATIBILITY
TruStability
®
products with the liquid media option have
additional protection applied to Port 1 to allow it to survive
exposure to condensing humidity and some liquids (see
Table 1).
Table 1. TruStability
®
Pressure Port Compatibility
Option
Port 1
Port 2
without
liquid
media
option
non-corrosive, non-
ionic media only
(such as air and dry
gases)
must not be exposed
to condensing
humidity
non-corrosive, non-
ionic media only
(such as air and dry
gases)
must not be exposed
to condensing
humidity
with
liquid
media
option
non-corrosive, non-
ionic liquids or gases
non-corrosive, non-
ionic media only
(such as air and dry
gases)
must not be exposed
to condensing
humidity
PORT 1 WETTED MATERIALS OF CONSTRUCTION
The following wetted materials of construction are exposed
materials in the media path:
High temperature polyamide
Silicone
Alumina ceramic
Silicon
Epoxy
Ceramic
Glass
Solder
The liquid media being used needs to be compatible with all
wetted materials used in the sensor construction (i.e., covers,
substrate, adhesives and electronic components). Even
though a liquid may be compatible initially, it is not
uncommon for some media to undergo chemical changes in
the application over time. If this is possible in the end user
application, the changed media also needs to be validated
as compatible with the wetted materials.
An example of this change is when a compatible gas, like
nitrogen dioxide (NO
2
), combines with high humidity to form
nitric acid (HNO
3
), which, at certain concentrations, will etch
the silicon sensor die and affect the sensor output. The
same thing may occur when water is present in combination
with NO
2
or other gases that create an incompatible working
liquid.
SENSOR PORT POSITIONING
Recommend that the sensor be positioned with Port 1
facing downwards; any particulates in the system are
less likely to enter and settle within the pressure sensor if
it is in this position.
Ensure liquid media contains no particulates. All
TruStability® sensors are dead-ended devices.
Particulates can accumulate inside the sensor, causing
damage or affecting sensor output.
Ensure liquid media does not create a residue when
dried; build-up inside the sensor may affect sensor output.
Rinsing of a dead-ended sensor is difficult and has
limited effectiveness for removing residue.
