There is but it doesn't seem to help - instructions say to loosen the nozzle:Is there a pressure relief valve on it, or something?
Amazon product page said:Important!
When you want to remove the nozzle from zerk fitting, it will be so hard to remove it. Please follow below steps, then you can remove the nozzle easily---
1. Untighten the hose or nozzle a little bit(this step unload the kept pressure in the hose/nozzle)
2. Remove the nozzle from the zerk fitting easily.
The issue is a nature of the regular greas gun and regualr nozzle, it is caused by the kept pressure in the hose/nozzle which will make the coupler clamp the zerk fitting tightly still, as long as there is no kept pressure in the hose/coupler, it will be easy for the user to remove the hose/nozzle from zerk fitting.
To avoid this situation in the long run, users can buy the manual unload couple, which will be easier for user to use this.