I have a Kimber pepperblaster that I brought to Spain from America when we moved here in 2016. Odds are it's 4 years old now, the shelf life Kimber claims for it. Does that mean the pepper concentrate is no longer viable? They say that the spray isn't pressurized so it can't lose pressure over time so I'm trying to figure out what dies on it after 4 years. BTW I can't just get a replacement. Pepper Spray is legal in Spain but only at 5% strength. The Kimber is 10%.