B73 & Series 75
Liquid Level Switches
Table of Contents
1.0 Installation
1.1 Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.2 Critical Alarm Function . . . . . . . . . . . . . . . . .1
1.3 Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.4 Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
1.5 Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
2.0 Reference Information
2.1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2.2 Theory of Operation . . . . . . . . . . . . . . . . . . .4
2.3 Operating Cycle . . . . . . . . . . . . . . . . . . . . . . .4
2.4 Switch Differential Adjustment . . . . . . . . . . .5
2.4.1 Low Level Controls . . . . . . . . . . . . . . .5
2.4.2 High Level Controls . . . . . . . . . . . . . . .7
2.5 Tandem Float Models . . . . . . . . . . . . . . . . . . .7
2.5.1 Installation, Preventive Maintenance,
and Troubleshooting . . . . . . . . . . . . . .7
2.5.2 Differential Adjustment . . . . . . . . . . . .8
3.0 Troubleshooting
3.1 Check Switch Mechanism . . . . . . . . . . . . . . .8
3.2 Check Sensing Unit . . . . . . . . . . . . . . . . . . . .9
4.0 Preventive Maintenance
4.1 What To Do . . . . . . . . . . . . . . . . . . . . . . . . .10
4.1.1 Keep Control Clean . . . . . . . . . . . . . .10
4.1.2 Inspect Switch Mechanisms, Terminals,
and Connections Monthly . . . . . . . . .11
4.1.3 Inspect Entire Unit Periodically . . . . .11
4.2 What To Avoid . . . . . . . . . . . . . . . . . . . . . . .11
5.0 Specifications
5.1 Agency Approvals . . . . . . . . . . . . . . . . . . . . .12
5.2 Physical . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
6.0 Replacement Parts
6.1 Series 75 . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
6.1.1 Parts Identification . . . . . . . . . . . . . . .17
6.1.2 Switch and Housing Reference . . . . . .17
6.1.3 Series 75 with Material Code 1 . . . . .18
6.1.4 Series 75 with Material Code 2 . . . . .18
6.1.5 Series 75 with Material Code 3 or 4 . .18
6.2 Model B73 . . . . . . . . . . . . . . . . . . . . . . . . . .19
6.2.1 Parts Identification . . . . . . . . . . . . . . .19
6.2.2 Switch and Housing Reference . . . . . .19
6.2.3 Model B73 . . . . . . . . . . . . . . . . . . . . .19
6.3 Series 75 Tandem Float Units . . . . . . . . . . . .20
6.3.1 Parts Identification . . . . . . . . . . . . . . .20
6.3.2 Series 75 Tandem Float Units . . . . . . .20
6.3.3 Switch and Housing Reference . . . . . .20
7.0 Model Numbers
7.1 Model B73 . . . . . . . . . . . . . . . . . . . . . . . . . .21
7.2 Model Series 75 . . . . . . . . . . . . . . . . . . . . . .23
