Technical Service Bulletins

Belleville Springs & Washers

D73321.10 Belleville Maximum Deflection Correction 2-13-2017
D73321.11 Belleville Hardness Correction 4-24-2018
D73321.12 Belleville Flat Load Correction 8-12-2019
D73321.13 H-13 Hardness Change 1-30-2020
D73321.14 Belleville Minimum Overall Height Correction 5-4-2020
D73321.15 New Solon Washer Tolerance Scheme 9-14-2020
D73321.16 Elimination of Black Oxide Finish on New H13 Flange Washers 
D73321.19 Standard 17-7PH Condition Now TH1050 Per AMS2759/3 Rev J 6-4-2024

Pressure Switches

D73321.01 Alarm not Resetting in 2TC Density Switches 5-21-2013
D73321.02 Reduced Settings in 2TC Density Switches 5-21-2013
D73321.03 Low Settings in 2TC Density Switches 5-21-2013
D73321.05 False Alarms at Elevated Temperatures in 2TC Density Switches 5-21-2013
D73321.06 Cover O-rings Cracking for 2TC Density Switches 5-21-2013
D73321.07 False Alarms at Temperatures Below 20°F in 2TC Density Switches 5-21-2013
D73321.08 Moisture Found in Pressure Gauges 12-13-2013
D73321.09 Erratic Microswitch Operation when using a Digital Continuity Tester 10-05-2015
D73321.17 Product Line Discontinuation Notice 8-29-23
D73321.18 Elimination of Painted Finish on Solon 5PS and 6PS Pressure Switches 

For questions regarding Technical Service Bulletins, please contact our Engineering team. 

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