Pressure & Differential Switches
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Series 100 Pressure Switches
• Non-bleed in either switched state
• Configurable for N.O. or N.C. output
• Compact and robust
• Aluminium or stainless steel construction
• High accuracy
A Pneumatic Output pressure switch
with Non-Bleed Two-Port Output
Switching.
These switches were designed for use
on monitoring systems associated with
natural gas transmission. Typically the
switch can be used to protect a system
or pipeline from an abnormally high or
low pressure which might result in the
discharge of gas.
The switch has an integral 2-port
changeover valve connected to a
regulated natural gas supply. As the
switch operates the output of this valve
changes between the regulated supply
pressure and zero. This output can be
used to control the operation of a valve
which would then isolate the system.
For low pressure switching the output
valve would typically be
configured as normally closed (N.C.) to
give an output above the setpoint
of the switch. This output is lost as the
process pressure falls below the setpoint.
For high pressure switching the output
valve would typically be configured
as normally open (N.O.) to give an output
below the set-point of the switch. This
output is lost as the process pressure
rises above the setpoint.
In either mode there is no continuous
bleed of gas in either switched state. The
only time gas is vented is during
switching as the output falls from the
supply pressure to zero. A tapped
connection is provided on the vent port
so that this gas can be piped away if
necessary.
With an anodised aluminium or 316
stainless steel construction only 121mm
long and 55mm diameter this Series 100
pressure switch is both compact and
robust. It provides high switching
accuracy with low switching differentials
(the change in process pressure required
to change the output). Standard ranges
provide setpoint adjustment pressures
from 0.1 bar up to 100 bar.
This pressure switch can also be used on
other applications requiring the switching
of any dry inert gas that is compatible
with the materials of construction.
Rototherm/HNL manufacture a wide range of pressure and differential pressure switches with both electrical outputs and pneumatic outputs. These include ATEX certified pressure switches suitable for use in hazardous areas.
Series 100, 300 and 700 are all mechanical pressure switches - the Series 800 pressure switch is an electronic device that also functions as a pressure indicator and transmitter. All are available with aluminium or stainless steel housings and a wide selection of process wetted parts.
Series 300 Standard Version
These pressure switches are designed to
provide electrical output switching for
non-hazardous area applications.
A large selection of output switches are
available providing the options listed
below:
• Fixed Differential
• Single (S.P.D.T.) or Twin Switch
(2 off S.P.D.T. effectively D.P.D.T.)
• Gold or Silver Contacts
Series 300 Pneumatic Version
Pneumatic Output Pressure Switches
provide the switching of a compressed
gas supply (generally air) at a
pre-determined pressure.
The different pneumatic output
switching options are listed below:-
Code 61 - the pilot supply is used to
operate a 3 port changeover valve.
This switch has a fixed switching
differential.
Code 71 - Primarily used for providing
an input into low pressure (1.4 bar / 20
p.s.i.) logic systems. This switch has only
two bulkhead connections - the pilot
supply and the output. The output switch
can be configured to provide an output on
either a rising or falling pressure.
Code 81 - as code 61 above but for lower
pressure operation.
Series 300 EExd Version
These pressure switches are designed to
provide electrical output switching for
Potentially Explosive Atmosphere
applications.
The Certifications available are listed
below:-
Exd Switches
(Cert. No: BAS07ATEX0090X)
Enclosures are certified Exd IIB+H2
T4/T5/T6 to EN60079-0 &
EN60079-1.
ExnC & ExtD Switches
(Cert. No: HNL07ATEX0001X)
Enclosures are certified EExnC IIC
T4/T5/T6 & ExtD A22 IP66 100°C to
EN 60079-0, EN 60079-15, EN
61241-0 & 61241-1.
Exia Switches
(Cert. No: Baseefa06ATEX0231X)
Enclosures are certified Exia IIC T5/
T6 to EN 60079-0 & EN 50020.
I.S. Compatible
Series 300 switches are classified
as simple apparatus, allowing use
in an I.S. circuit without individual
certification.
Series 800
The Series 800 Smartstat is a microprocessor controlled switch, transmitter and indicator, which enables several instruments to be replaced with a single device. Smartstats are available for the measurement of pressure / differential pressure (P & DP) and temperature (T).
Replacing a transmitter, switches and a gauge with a single Smartstat reduces equipment costs. Additionally there are reductions in documentation, installation time/ fittings/cabling, and calibration/maintenance costs.
Increased Accuracy/Repeatability
The Smartstat provides greater accuracy and repeatability than a conventional mechanical switch. Very large and very small switching differentials can be achieved without compromising accuracy.
Ease of Calibration
Pushbutton calibration of switch setpoints and 4-20mA calibration can be carried out on site without additional test equipment or tools.
Additional Features
Because the Smartstat is microprocessor based additional features are easily provided through the software including:
• Programmable switching delays - the switching on or off (or both) of the relays may be delayed from 0.5 seconds to 15 minutes. This is particularly useful for preventing unwanted switching due to pressure transients.
• Display of MAXimum and MINimum pressures recorded by the Smartstat.
• Display of transmitter output in mA.
• Reversal of transmitter output 20-4 mA instead of 4-20 mA.
• Square-root extraction to provide 4-20mA output proportional to flow using a DP Smartstat.
• Displayed units of measurement - can be changed by the user as required.
Series 800 Smartstat Pressure Switch
There are some pressure switching
applications that are very demanding due
to the need for:
• Very high (or low) pressures.
• High accuracy and repeatability.
• Very large (or small) switching differentials.
• High frequency switching operation.
• Low frequency switching operation (once per year).
• Regular need to change switching pressures.
These requirements may exceed the
capabilities of conventional mechanical
pressure switches, the Smartstat was
designed to overcome these problems.
• Smartstat ranges extend from 15 mBar up to 1000 Bar.
• Typical accuracy is 0.1%.
• Two independent single-pole, double-throw (SPDT) relays are fitted in the Smartstat, the operating points of which can be set anywhere within the range. The switching differential can be set from 1 digit to 100.0% of range without loss of accuracy.
• Being almost entirely ‘solid state’ the Smartstat can provide up to 100,000,000 switching operations whilst operating at up to 120 times per minute.
• Pushbutton calibration of switch setpoints can be carried out on site without additional test equipment or tools.
•With a mechanical switch testing the operation regularly is the only way to ensure that it is operating correctly. With the Smartstat the continuous pressure display serves to indicate that the device is operating correctly and will switch when required.
• In addition to its function as a high accuracy pressure switch the Series 800 Smartstat also functions as a pressure transmitter and pressure indicator enabling significant cost savings as several instruments can be replaced with a single device.