AMS FS1790 Installation Operating & Maintenance Manual Download Page 3

©AM SENSORS LTD

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AMS-S-082/DS/09.2016 (ISSUE 2)

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

Summary of Contents for FS1790

Page 1: ...INSTALLATION OPERATING MAINTENANCE MANUAL HORIZONTAL FLOAT SWITCHES TYPE FS1790 ...

Page 2: ...se 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 ...

Page 3: ...ontacts 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 relia...

Page 4: ...o 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 ensur...

Page 5: ...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 str...

Page 6: ...g 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 termina...

Page 7: ...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 c...

Page 8: ...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...

Page 9: ... AM SENSORS LTD 14 15 AMS S 082 DS 09 2016 ISSUE 2 EC Declaration ...

Page 10: ... 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...

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