I recently read that synthetic oils are more fire resistant and would like to know how much safer it would be to use synthetics in the hydraulic systems of machines working in a forestry application. How much less likely is a hydraulic oil leak to start a fire on the machine if synthetic oil is spilled onto a hot engine?

Rick: Not too much different. I looked at diesters and PAO, they have a little advantage, but not worth the money. You should consider a diethylene glycol/water additive package. Do use caution here, as the water evaporates, you will loosed fire protection. You need to obtain at least a 40% water to oil ratio.
TB

Rick M:

I would have to agree with Terry about PAO'S not being worth the money. On the other hand i have to disagree with him about using a water glycol fluid in any mobile equipment. I would not use it in any machine because they are hard on them. I would look at something that is called Ucon Trident. It has a fire point of 545 degrees and has a lot of benefits to it. It can wrap up 25,000 PPM of water and on the other hand it spilt in water it leave NO Sheen what so ever. It was made for your type of applications. Look at Americanchemtech.com web site to see more about it, you will be suprised. I have seen it work in a lot of applications.

Rick M,

Fire resistant doesn't necessarily mean fire proof. Most fire resistant fluids has a Factory Mutual (FM) approval. It really looks at the propagation and sustaining of the flame. An SFP rating or Spray Flammability Parameter is given. The old standard used to be 0, 1 and 2 (not sure if this has changed). Group 0 was non flammable, Group 1 - usually unable to stabilise a flame and group 2 - less flammable than mineral oils but may stabilise a spray flame under certain conditions. There are a number of fire resistant fluid classification HFAE - oil in water emulsion, HFB - water in oil emulsion, HFC - water glycol, HFDR- phosphate esters and HFDU - polyol esters. Obviously the ones with water is less flammable but also requires maintenance. The problem with glycol is that is toxic to the environment and also requires a degree of maintenance. Phosphate esters are also environmental hazards, is toxic and requires compatibility with seals, paints etc. In our part of the world, it is classified as a class 9 dangerous goods so there are disposal issues. The last one being the polyol ester is used where minimum fuss with material compatibility was required and the previous oil say a mineral oil. The use of fire resistant fluids should be carefully considered once a risk assessment has been done also considering what other mechanical fire prevention systems are in place. Most major oil suppliers will have a range of these products. I hope this helps.

You might check out Houghton International. They are the industry leaders in fire resistant hydraulic oils.

THe information about HFD-U oils is correct. To my knowledge, modern HFD-U fire resistant hydraulics are also biodegradable! So, they are good to be use in forestry, where besides fires you lessen the risk of damaging the environment.

Let me know if you need to know some suppliers.

Castrol's HFD-U fluid is readily biodegradable as an ISO 46 grade, and inherently biodegradable as an ISO 68 grade. Based on the definition that readily biodegradable biodegrades >80% after 28 days by OECD 301B. Products are Anvol SWX 46 and 68 respectively.

Dear All

I am very much with Rene WA.

Polyol Ester as best Fluid in terms of Fire Resistant Hydraulic Oil.

infact it will give high pump life . It has also very high Viscosty Index (215)

It is also maint. free .

It is also approved by Factory Mutual.

For more info please mail me at rrsdelhi@gmail.com

Regards

Rajeev