What is the trigger valve kit number for the Bostitch model BT1855K brad nailer? Wilson October 03, 2020 18:18 The trigger valve kit # is TVA15. Related articles My Bostitch pneumatic tool leaks air from the trigger area when I actuate the trigger, and the tool will not cycle. When the trigger is released, the leak will stop. What are the most common causes? Comments 0 comments Please sign in to leave a comment.