Emerson Process Management M310/FSM, Rev AA manual Product Description, Level Switch Purpose

Page 7

Horizontal Float Switch

Functional Safety Manual

M310/FSM, Rev AA

January 2012

PRODUCT

DESCRIPTION

Level Switch Purpose

Mobrey magnetic level switches are ideal for high and low liquid level alarm, overfill

 

alarm, and pump control duties.

Figure 1.

Application Example:

High and Low Level Alarm

Operation Principle

The level 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 fluid level is below the Switch Point, contacts B-B are made and contacts A-A are open (Figure 2).

When the process fluid level is above the Switch Point, contacts A-A are made and contacts B-B are open (Figure 3).

Figure 2.

Level Decreases –

Float Pivots Downwards

Contact B-B

Pushrods

N

 

s

N

s

 

 

 

 

 

 

 

 

Float

 

Contact A-A

 

 

Magnet

Cross-section of the Level Switch

Float

6

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Contents
Functional Safety Manual Mobrey Magnetic Level SwitchesPage Contents Introduction Scope and Purpose of the Safety ManualSkill Level Requirement Terms, Abbreviations, And Acronyms Low demand Functional SafetyDocuments Purpose of Documents Documentation and StandardsStandards Purpose of Standards Product Description Level Switch PurposeOperation Principle Ordering Information Cross-section of the Level SwitchContact B-B Pushrods Safety Function Environmental Limits Designing a Safety Function Using the Level SwitchApplication Limits Design Verification Random Integrity Safety ParametersSIL Capability Systematic IntegrityInstallation and Commissioning Operation and Maintenance Useful Life SpecificationsUseful Lifetime Step Proposed PROOF-TEST ProcedureSuggested Proof-test Proof Test CoverageLevel Switches Certified to IEC Typical Model Number S 250 D a / F84 Typical Model Number S 01 DB / F84Mobrey Level Solutions
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