SALE - Honest Phil Indicator - 3500 PSI - Gifts under $10

The Honest Phil Indicator (for 3500 PSI working pressure scuba cylinders) is a must have for any diver that has their own scuba tanks. Specifically designed to promote slower tank filling which reduces pressure drop (also called “short fills”).


Simple, yet highly effective additional benefits include improved pre-dive planning and longer scuba tank life. Rapid fills can cause cylinders to fail hydro many years before they would under normal use (especially Aluminum tanks). Additionally, having a “full tank” at the start of the dive has a long list of obvious benefits.

Every diver has had it happen: You get your tank filled, prep for your dive, get your equipment together, get your friends together, go to the dive site (boat, etc.). Get suited up and all ready to dive only to check your gauge and find your cylinder's pressure shows you have less than you thought. You know that when you had your tank filled it registered as full at the time. Now the pressure is lower. Maybe it is just a small drop in pressure, maybe it is a significant decrease. Until now, there was no simple way to know what pressure drop your tank might experience from an air fill. Honest Phil can tell ahead of time. Here's how:

Honest Phil Pressure Drop Indicator is an inexpensive, yet sophisticated sticker that is applied near the neck of a scuba tank in order to promote a slower air fill. The sticker has temperature sensitive ovals that turn clear as the tank heats up revealing the pressure differential below. This is a sign of a rapid fill, also called “hot fills”.

A thermometer range on the left side of 'Phil' allows you to note the tank's approximate temperature (in 5° F/3°C increments). The higher the temperature, the more ovals will clear. The visible number within the highest clear oval is the approximate pressure drop you can expect when the tank returns to room temperature (70° F/21°C). The slower a tank is filled, the less of a temperature increase there is. The less the temperature increases, the more air you have for your dive!

The size (volume) of the tank does not make a difference. The same pressure drop will occur regardless if used on a small pony bottle or twin 120 cubic foot twins. This is because the volume is constant once the tank is filled and the valve is closed. Air is not going in or out of the tank.

Salt water safe, for use with both Steel and Aluminum Tanks. Order the model that matches your tanks stamped working pressure. Available in five pressures, 2250 PSI, 2400 PSI, 3000 PSI, 3300 PSI or 3500 PSI.