AMS FS1790 User manual
INSTALLATION, OPERATING
& MAINTENANCE MANUAL
HORIZONTAL
FLOAT
SWITCHES
T Y P E: FS179 0
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AMS-S-082/DS/09.2016 (ISSUE 2)©AM SENSORS LTD
Contents
1. Safety Instructions .................................................. 1
2. Functional Description .......................................... 2
3. Area of Application .............................................. 3
4. Installation ............................................................ 4
5. Electrical Connections ......................................... 7
6. Commissioning / Functional Testing .................... 11
7. Maintenance ...................................................... 12
8. Technical Data .....................................................13
9. EC Declaration .................................................... 14
1. Safety Instructions
Read these instructions before installing the ATEX Group I Horizontal float switch
and placing it into operational service.
These instructions are intended for the personnel responsible for the installation
and commissioning of the float switch.
Comply with the relevant safety regulations when using the equipment.
Do not install the float switch in the immediate vicinity of any strong
electromagnetic fields (recommended min distance >1 meter).
Do not subject the float switch to heavy mechanical loads.
AMS-S-082/DS/09.2016 (ISSUE 2)©AM SENSORS LTD.
WARNING:
Failure to comply with the instructions described within this manual
can lead to malfunction or damage to the switch and if the switch is
incorrectly installed the ATEX certification may be void.
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2. Functional Description
AMS magnetic float switches are ideal for high and low liquid level alarm,
and pump control duties. These Liquids should not contain heavy soiling or
coarse suspended matter and must not show a tendency to crystallize when
drying out. If the liquids that the float switch is being used to measure do have
conditions as listed above then routine maintenance should be carried out to
ensure the float can still pivot on the guide tube.
The ATEX Group I Horizontal float switch is designed to open or close a circuit
(“switch”) as a changing liquid level within a vessel passes the level of the float
(the Switch Point).
When the process liquid level is below the Switch Point, the contacts are either
open circuit (NO) or closed circuit (NC) depending on the switch configuration
as determined by the customer, when the liquid level raises the float will
become buoyant and as the liquid level increases passed the switch point the
contacts will change over.
The float arms have an in- built magnetic which operates the reed switch
contact through the wall of the guide tube. Thus the switching operation is
without direct contact to the liquid, free of wear and tear, and does not require
any power supply.
Benefits of using AMS Magnetic Float Switch Technology
i) Over 40 years of experience – a proven design (Ex Alan Cobham)
ii) Simple, reliable, and cost effective level measurement technology
iii) Tough, rugged design for long life in aggressive environments
iv) Operates in almost any liquid at high pressures and temperatures
v) Measurement is unaffected by changes in process temperature,
dielectric, or the presence of vapours
An approval has been issued for the FS1790 ATEX Group I Horizontal float
switches for use as explosion-protected equipment within the scope of
application defined by EU Guideline
94/9/EC ATEX in hazardous areas.
They comply with the specifications concerning equipment and protective
systems intended for use in potentially explosive atmospheres.
THE TECHNICAL DATA IN THIS OPERATING INSTRUCTION MUST BE COMPLIED WITH.
FS1790 Float Switches carry the following ATEX Certification plate:
3. Areas of Application
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4. Installation Installation
4.1 Removal of transport packaging
Remove the float switch carefully from the transport packaging; never forcibly
remove the float switch from the packaging.
Always handle the float switch by the switch body and /or by the mounting
flange.
Do not lift the float switch up by the float or float arm as this could cause the
tube to bend and invalidate any warranty.
Remove the temporary bolts holding the float switch body to the float arm
assembly and gently separate the 2 components.
4.2 Installation
The ATEX Group I horizontal float switch type FS1790 is designed to be solely
installed in the horizontal position, do not attempt to install this switch design in
the vertical position as the float will not operate the reed switch.
Prior to installing the float switches confirm that the vessel has the correct
mounting arrangement for the float switch. The suggested method of
mounting the float switch to the vessel is shown in Fig 1.
Insert the float arm assembly (Item 3- Fig 2) through the Ø68mm vessel
aperture ensuring that the assembly is aligned with the locating dowel
confirming correct switch orientation and slide over the mounting studs until it is
seated on the gasket (customer supplied).
Holding the float arm assembly in position, insert the float switch body (item 1-
Fig 2) and gasket (item 2- Fig 2) through the float arm assembly, align the float
switch cable entry flange so that it is facing vertically.
Fix in place using suitable nuts and washers and tighten to specific torque
rating for the studs.
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Installation 5. Electrical Connections
WARNING:
It is essential that the electrical supply to the switch does not exceed the
electrical rating of the reed switch and that loads in excess of the maximum
reed switch operation are not applied.
Ensure the switch is not operated outside its designated temperature range
(see label).
5.1 Installing the Cable Gland
If ordered with the switch, install the cable gland flange FS4825 to the ATEX
Group I float switch using the M8 x 35mm Bolts, Nuts and washer (supplied
with the flange), ensuring that a suitable gasket is installed between the flange
faces (not supplied) as shown below.
The cable gland flange FS4825 is designed to take a M25 x 1.5 ATEX rated
cable gland, install the cable gland onto the cable gland flange FS4825,
ensuring that the manufactures instructions are strictly followed.
Vessel Mounting
Arrangement as
shown in Fig 1
Item 3 –
Float Arm Assy
Item 2 –
Gasket (Supplied)
Item 1 –
Float Switch
Body
Orientation
Hole
FS4825 M25
Cable Gland
Flange
(Optional)
Gasket
Float Switch Assembled View
Installed on to the Vessel
Fig 2:
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Electrical ConnectionsElectrical Connections
5.2 Switch terminal Access
Undo the 4 off M10 socket headed screws and spring washers (Item 1), and
while holding the float switch body, carefully lift the lid (Item 2) in an linear
direction (gently rotating clockwise and anti-clockwise aids removal of the lid).
Remove the terminals and terminal base (Item 3) in an upwards direction,
being careful not to put any strain on the switch wiring.
Once the switches have been terminated to the system, gently insert the
terminals and terminal base (Item 3) back into the float switch body; replace
the lid (Item 2) onto the body making sure that the O-ring is not trapped.
Replace and tighten the 4 off M10 socket headed screws (Item 1), to no
greater than 10 Lbs. torque.
5.3 Switch Wiring Configuration
Single pole / double throw switches (options) are terminated using 3 wires;
these wires have the following colours and configuration:
Common Wire Red Wire
Normal Closed Contact Blue Wire
Normally Open Contact Orange Wire
The switch wires are terminated to a four way terminal block in the following
configuration:
Item 1
Item 2
Item 3
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6. Commissioning
/ Functional Testing
Electrical Connections
5.4 Earthing Flameproof Versions
The Flameproof Float switch has 2 earthing points, the internal earth point is
provided in the float switch lid, while the second earthing point is external to
the float switch on the body.
Both earthing points have an earthing tag secured in place with a Stainless
Steel M6 socket headed bolt and spring washer.
All switches should be earthed correctly to maintain the ATEX certification.
Functional Testing – FS1790
Before the float switch is installed, it can be checked for functionality using a
continuity checker or ohmmeter.
i) Assembly the float switch body and float arm assembly, temporarily
using the shipping bolts to hold it assembled.
ii) Remove the terminal cover lid as described in section 5.2.
iii) Connect the continuity checker to the wires for the switch (switch
configuration as shown in section 5.3).
iv) Lift the float in an upwards direction and confirm that the switch
changes state.
v) Let the float gently return to the original position (horizontal to the float
arm baffle plate) and confirm that the switch has changed state.
Commissioning
Once installed the ATEX Group I Horizontal float switch can only be tested from
the vessel internally or tested with the liquid level rising / falling in the vessel. It is
therefore recommended that the FS1790 float switch is functional tested before
the switch is installed in the vessel.
WARNING:
When the FS1790 is being used in an explosive atmosphere, any supplies to
the switch MUST be isolated before removing the float switch lid.
Earthing Tag
Float Switch Lid
Float Switch Body
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7. Maintenance 8. Technical Specifications
The ATEX Group I Horizontal float Switches are designed to give long periods
of satisfactory trouble-free life, and under normal conditions, they require little
maintenance.
Where switches are used in liquids having a tendency to form deposits or
in the case of some oils, there is a tendency for a ‘varnishing’ effect to be
produced on the immersed section of the stem tube and float. If this occurs,
it is advisable to remove the unit and remove any deposits likely to hinder the
float operation.
AMS recommend that the ATEX Group I Horizontal float switch FS1790 is
periodically functional tested every 6 months to confirm operation, if the
process medium contains heavy soiling or coarse suspended matter it is
recommended to reduce this testing interval, to confirm that the float still has
free movement and is not obstructed from operating.
If the switch fails to operate, the unit should be returned to AM Sensors along
with a completed declaration returns form (this form is available upon request).
RS13 Reed Switch
Switching Action SPDT (Change over option)
Switching Voltage 400 V AC/DC
Switching Current 1.0 A Max
Max. Power: 60 Watt 60 Watt
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EC Declaration
©AM SENSORS LTD
AMS reserve the right to make technical changes or modify the contents of this document without prior
notice. With regard to purchase orders, the agreed particulars shall prevail.
AMS does not accept any responsibility whatsoever for potential errors or possible lack of information
in this document.
AMS reserve all rights in this document and in the subject matter and illustrations contained therein.
Any reproduction, disclosure to third parties or utilization of its contents - in whole or in parts - is
forbidden without prior written consent of AMS.
AMS-S-082/DS/09.2016 (ISSUE 2)
AM Sensors Ltd,
Chedzoy Lane, Chedzoy,
Bridgwater, Somerset
TA7 8QS
t+44 (0)1278 444 650
f+44 (0)1278 434 449
einfo@amsensors.com
www.amsensors.com
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