| FREQUENTLY ASKED QUESTIONS |
What is the effect of lowering the freezing point of water when treating fuel with PRIST® Hi-Flash™ Fuel Additive?
What will PRIST® Hi-Flash™ Fuel Additive do and what will in not do?
How does PRIST® Hi-Flash™ Fuel Additive work?
What is the issue with Monitor type filters?
What if I have Monitor type filters on my trucks or last point of filtration?
What biocidal/antifungal properties does the PRIST® Hi-Flash™ Fuel Additive have?
What aircraft require PRIST® Hi-Flash™ Fuel Additive?
As a Pilot of an aircraft that requires PRIST® for safe flight, how can I ensure that I am getting the additive and at the correct concentration?
What types of packages is the product available in?
What is the difference between the PRIST® Hi-Flash™ Hi-Flo™ vs. PRIST® Hi-Flash™ Lo-Flo™ additive aerosol products?
Does the PRIST® Hi-Flash™ Fuel Additive fall out of fuel?
Does the PRIST® Hi-Flash™ Fuel Additive have a shelf life?
What is "apple jelly" and where does it come from?
What is the effect of lowering the freezing point of water when treating fuel with PRIST® Hi-Flash™ Fuel Additive?
The freezing point of the water suspended in the fuel is lowered to minus 46° F when PRIST® Hi-Flash™ Fuel Additive is used. This is true for fuel that is within ASTM and MIL specifications, with regards to water content in the fuel.
The freezing point is also dependent upon the concentration of DiEGME (active ingredient in PRIST® Hi-Flash™ additive) in the fuel which should be between 0.10 and 0.15% by volume when mixed properly per instructions.
What will PRIST® Hi-Flash™ Fuel Additive do and what will in not do?
PRIST® Hi-Flash™ is an aviation fuel additive that is designed to prevent water from freezing and thereby preventing fuel starvation in-flight.
When applied correctly, in conjunction with the fuel being maintained correctly, PRIST® Hi-Flash™ will stay in solution indefinitely. PRIST® Hi-Flash™ will not change the freeze point of fuel; it simply encapsulates water droplets that form in fuel, altering their freeze point.
PRIST® Hi-Flash™ is not a “tank cleaner” or a “fuel purifier”, it will not eliminate water nor will it replace the need for good housekeeping of fuel which requires daily sumping and removing of water and particulates. Lastly, PRIST® Hi-Flash™ IS NOT a biocide and it will not “KILL” microorganisms.
How does PRIST® Hi-Flash™ Fuel Additive work?
The PRIST® Hi-Flash™ Fuel Additive product is hygroscopic, which means it seeks out moisture, the product then works by encapsulating water droplets that form as fuel is cooled and keeps the water droplets from freezing.
Although readily soluble in water the additive has limited solubility in fuel, therefore it is imperative that the additive be applied to the fuel correctly.
Furthermore, this is why the requirement exists that the additive be kept dry and containers closed, if a container is to be vented, the vent should be equipped with a functioning desiccant dryer. (Picture of Desiccant Dryer)
What is the issue with Monitor type filters?
Industry filter manufacturers do not recommend the use of Monitor type – water absorbing filters in the presence of Pre-Blended fuel. The reason is that these water absorbing type filters do their job in absorbing water, we know that PRIST® Hi-Flash™ Fuel Additive seeks out and encapsulates water. As this naturally occurs, concentrations of PRIST® Hi-Flash™ Fuel Additive can be found on the Monitor element and may cause it to not function properly by eliminating its ability to provide a water defense. Even worse, because PRIST® Hi-Flash™ Fuel Additive is a strong solvent, it may cause the deterioration of the actual components of the Monitor allowing fibrous material to be extruded from the element and migrate downstream.
If purchasing Pre-Blended fuel is desired, all filtration must be of the Particulate Filter/Water Coalescing type with a mechanical water defense system.
What if I have Monitor type filters on my trucks or last point of filtration?
The two choices are 1) Inject PRIST® Hi-Flash™ Fuel Additive downstream of the final filter to those aircraft requiring PRIST® Hi-Flash™ Fuel Additive for safe flight, or 2) With the use of Pre-Blended fuel, you must convert all filtration to Filter/Water Coalesors.
What biocidal/antifungal properties does the PRIST® Hi-Flash™ Fuel Additive have?
PRIST® Hi-Flash™ Fuel Additive meets ASTM D4171 and MIL-DTL-85470 (Current Revision Issue) specification for DiEthylene Glycol Monomethyl Ether (DiEGME). The primary purpose of this chemical is to prevent freezing of water in the fuel system of aircraft. It is this property that is covered in ASTM and/or Military specifications. Neither of these specifications contains any biocide requirements.
Prior to 1994, PRIST® was made to a Military Standard MIL-I-27686, which specified Ethylene Glycol Monomethyl Ether (EGME). Provisions were made to have this product certified as a pesticide with the EPA. This allowed the product to be advertised as having the ability to retard growth of microbes in aviation fuels. The correct term is for the additive is microbiostat (-stat means it controls or retards growth by putting the microbes in a static condition), it is not a true microbiocide, (-cide means it kills microbes).
With all of the new EPA requirements, it became economically prohibitive to certify the new DiEthylene Glycol Monomethyl Ether, DiEGME based additive as a pesticide. Summarizing the above, it is widely believed that DiEGME does have a retarding effect on microbial growth; however, we no longer officially claim this property for the PRIST® Hi-Flash™ Fuel Additive.
What aircraft require PRIST® Hi-Flash™ Fuel Additive?
PRIST® Hi-Flash™ Fuel Additive is not required by all aircraft BUT is MANDATORY for safe flight by some, namely:
- Aerospatiale/Mooney - TBM 700
- Beechcraft Raytheon - Beechjet 400 & Starship’s
- Bombardier Learjet - 23-24-25-28-29 & 35/36 Series
- Cessna Citation – Caravan, Corsair/Conquest, Citation I & II
- Hansa – HFB-320
- Mitsubishi - MU-2 Series & MU-300 Series
- Piaggio - Avanti
- An ever increasing number of Very Light Jets (VLJs)
As a Pilot of an aircraft that requires PRIST® for safe flight, how can I ensure that I am getting the additive and at the correct concentration?
Some fueling locations offer “Pre-Blended” or “Additized” fuel that is delivered to them with the additive already mixed into the fuel at time of delivery to the airport.
At these locations you can ask to see the delivery documentation that should verify the application and concentration of the PRIST® Hi-Flash™ in the fuel. These locations should also have documentation that they perform regular Refractometer testing (B-2 test) of the fuel, at the delivery point, to ensure the proper concentration of PRIST® Hi-Flash™ is being delivered to the aircraft. At fueling locations that apply the PRIST® Hi-Flash™ additive during the actual fueling operation, it is easier to verify the additive is being applied.
There are several things that may be observed during the fueling operation, they are:
- Ensure the additive control selector is in the “ON” position
- Observe the “Sight Flow Indicator” to see additive flowing
- Look to see that there is ample supply in the additive reservoir
You may even be able to see the additive supply diminishing as additive is being injected during the fueling operation. The additive supply should also have a functioning desiccant dryer on the vent to keep the vented air dry.
These locations that inject during the fueling operation should also have documentation of regular calibration of their additive injection system and perform regular (B-2) Refractometer testing of the fuel, at the delivery point, to ensure the proper concentration of PRIST® Hi-Flash™ is being delivered to the aircraft.
Some fueling trucks are equipped with automated systems that when the additive control has been place in the “ON” position, should the application of the PRIST® Hi-Flash™ additive fall below the correct injection ratio of 1000-1500 PPM, the pumping system stops in a “fail-safe” mode.
What types of packages is the product available in?
PRIST® Hi-Flash™ Bulk is available in 350 and 250 gallon “TOTES” or “CARBOYS”, these containers are commonly used by fuel terminals or large users who have the ability to turn this size inventory container more than four times per year. (Average treated fuel usage will be greater than 1m gallons per year)
PRIST® Hi-Flash™ 55 Gallon Drums are the most common of all the containers offered.
PRIST® Hi-Flash™ 5 Gallon Pails
PRIST® Hi-Flash™ “Hi-Flo” Fuel Additive is the same standard of quality in aviation fuel anti-icing packaged in an aerosol can. Prist® Hi-Flo is specifically packaged to deliver the correct amount of additive for use with aircraft refueling system that flow at rates of 30 to 60 gal/min. 20-oz. aerosol cans are packaged 6 to the box/24 to a case and may be transported in aircraft cargo hold of aircraft. (Photo of 20-oz. can in front of case)(Photo of case being removed for aircraft cargo hold)
PRIST® Hi-Flash™ “Lo-Flo” Fuel Additive is the same standard of quality in aviation fuel anti-icing packaged in an aerosol can. Prist® Hi-Flo is specifically packaged to deliver the correct amount of additive for use with aircraft refueling system that flow at rates of 15 to 20 gal/min.
What is the difference between the PRIST® Hi-Flash™ Hi-Flo™ vs. PRIST® Hi-Flash™ Lo-Flo™ additive aerosol products?
PRIST® Hi-Flash™ Hi-Flo Anti-Icing Aviation Fuel Additive is chemically identical in formula to PRIST® Hi-Flash™ Lo-Flo Anti-Icing Aviation Fuel Additive. Hi-Flo additive simply means the can delivers at a rate compatible with a 40 to 55 gallon per minute fuel nozzle rate while Lo-Flo additive cans deliver at a rate which is typical of AvGas or 15 to 30 gallon per minute. Lo-Flo additive is also used in helicopters which typically have to be fueled slowly.
The PRIST® Hi-Flash™ anti-icing additive, DiEthylene Glycol Monomethyl Ether, is approved for addition to turbine fuel under ASTM specification D1655 and for aviation gasoline (AvGas) under specification D910. The additive is exactly the same for both turbine fuels and aviation gasoline.
The additive itself is produced to ASTM specification D4171 and to the Military Spec MIL-DTL-8570B. The Lo-Flo additive product is no longer available.
Does the PRIST® Hi-Flash™ Fuel Additive fall out of fuel?
If the additive is applied correctly, PRIST® Hi-Flash™ additive will remain in the fuel phase. PRIST® Hi-Flash™ will only come out of solution when it comes in contact with water; water can occur in fuel from condensation which happens due to temperature swings from hot to cold or in the form of FREE or bulk water. Keeping water bottoms in storage tanks and low point drains in filter systems will go a long way toward ensuring PRIST® Hi-Flash™ stays in the fuel where it is required for safe flight for some aircraft.
Does the PRIST® Hi-Flash™ Fuel Additive have a shelf life?
As long as it is stored correctly, PRIST® Hi-Flash™ has no shelf life. It is important that it be kept as dry as possible and that the container remains sealed to prevent contact with water or moist air. Because of its natural tendency to seek out water, its effectiveness will be greatly reduced if it comes into contact with water in any way.
If the container rusts, is punctured, or the cap is left off, it can compromise the quality of the product and should not be used unless analyzed for chemical content. When venting this product, a desiccant dryer must be applied to the inbound vented air to remove moisture.
What is "apple jelly" and where does it come from?
Apple Jelly is light amber to dark reddish-brown gelatinous substance in aviation jet fuel that offers the appearance of a viscous material which can be problematic as it relates to the clogging of fuel filters.
Laboratory research reports indicate a potential link between excess water in fuel systems, PRIST ®/FSII/DiEGME, and a sodium producing substance, such as the static dissipating additive known as Stadis 450.
Proper storage and application of PRIST®/DiEGME in addition to adequate filtration points and proper quality control procedures need to be reviewed and possible improvements considered in order to avoid the formation of Apple Jelly. Southwest Research Institute developed the following working description of Apple Jelly:
“Apple Jelly is a variably fluid matrix comprising of water, Di-EGME, and other components originating from the jet fuel and any additives contained therein. The exact identity of the other components has yet to be well defined but may include metal salts (e.g. sodium, iron, calcium, potassium, and magnesium) of acid corrosion inhibitors, components from static dissipater additives, materials leached from elastomers, or metabolites originating from microbial activity. The color of apple jelly ranges from light amber to reddish-brown.”
In the C4e Report “C4e Field Investigation Into the Causes and Potential Solutions of Apple Jelly Formation in JP-8”, the C4e Investigation Team members involved in the project experienced significant quantities of Apple Jelly where excessive water in the fuel had been received or rainwater intrusion into military “on-base” tanks.
Quality Control and a strong focus on keeping fuel dry and protecting the integrity of their filtration systems should be maintained, in addition to keeping the additive dry before injection.