WATER GLYCOL HYDRAULIC FLUID 3

[STEELMAN]

I AM CURRENTLY USING HOUGHTON 419R WATER GLYCOL HYDRAULIC FLUID IN A 1000 GAL. RESERVOIR. REXROTH VARIABLE DISPLACEMENT AXIAL PISTON PUMPS HAVE BEEN FAILING PREMATURELY, ONE AFTER ONLY 120 HRS. OIL ANALYSIS REPORTS CONFIRM NO CONTAMINATION.REXROTH SAYS THE FLUID IS LOSING IT'S LUBRICITY. HOUGHTON SAY'S THE FLUID IS FINE. HOW CAN I TEST THIS FLUID FOR IT'S LUBRICATING PROPERTIES AND GET TO THE BOTTOM OF THIS FINGER POINTING MATCH?

 

[STASZEK]

Hello Steelman,<br><br>If you did not find a solution to this problem yet the best way is to find a suitable laboratory (i.e) US Steel (?) and conduct an independent test of this particular water-glycol in accordance with ASTM2882 ( Vickers vane pump test ) .<br>This is a standard test allowing comparison of wear<br>properties between different type of Fluids .Most of fluid suppliers quote&nbsp;&nbsp;test results in their brochures.<br>It will be easy then to compare the results.<br>The test may cost a few thousand dollars .<br>I have a similar problem and would like to hear from you .<br><br>Regards<br><br>Stan<br>

 

[NavyEcoEngineer]

In the Navy I found MilSpec Data Sheets differred greatly from Manufacturer Product Technical Properties Data Sheets provided to the civilian sector (For the same product)... <br><br>The MilSpec Data sheets from each manufacturer REQUIRED ALL had to provided specs using THE SAME TEST PARAMETERS in order to make a true determination as to true QUALITY and PERFORMANCE of lubricant for a specific application. <br><br>As an example take an BIODGRADABLE Hydraulic Oil<br><br>REQUIRED TEST SPECS<br><br>ISO VG - ASTM D-2422 = 32/46<br>SAE Grade = 5w-20<br>Viscometrics 100 Deg. C, cSt - ASTM D-445 = 7.69<br>Viscometrics 40 Deg. C, cSt - ASTM D-445 = 40.63<br>Viscosity Index (VI) - ASTM D-1298 = 161<br>Specific Gravity - ASTM D-1298 = 0.0047<br>Density - ASTM D-1298 = 7.534<br>FOUR-BALL WEAR TEST - ASTM D-4172 @ 40kg, 1200 rpm, 75 Deg. C, 1-Hour = 0.39<br>Flash Point (Deg. C) Deg. F ASTM D-92 = (206 C) 402 Deg. F.<br>Fire Point (Deg. C) Deg. F ASTM D-92 = (222 C) 431 Deg. F.<br>Poor Point (Deg. C) Deg. F ASTM D-97 = (-47 c) -52 Deg. F.<br>Copper Strip Corrosion Test ASTM D-130 = 1A<br>Foam ASTM D-892 Sequence I = 0/0, Sequence II = 0/0, Sequence III = 0/0<br>Demulsibility ASTM D-1401 Oil/Water/Cuff(minutes) = 40/40/0(25)<br>Dielectic Strength, KV - ASTM D-887 = 38<br>BIODEGRADABILITY % - CEC L-33-T-82 Within 21 Days = 80%<br><br>To bad they don't make all lubricant manufacturers including motor oil use standardize testing and labeling...<br><br>A lot of consumers would really be shocked at what they are really NOT getting for their money...the truth...<br><br>As an example Mobil 1's NEW and IMPROVED Tri-Synthetic motor oil does not provide as good of wear protection than the older formula did... just one more reason for standardized testing and labeling... label won't fit on container... no problem post it on their corpoarate website for everone to see...<br><br>Have A Fine Navy Day... <br><br><br><br><br>&nbsp;

 

A quick question which may point you in the proper direction. What is the operating pressure on the system and at which temperature does the system operate? Most WG fluids are able to run up to 2500psi max as the polimers can only withstand those pressures before the lubricity declines. With a higher pressure fluid with better polimers you should be able to decrease cavitiation, and allow longer fluid and system component life.

 

[romke]

120 hrs is somewhat less then expected...however, you should be aware that water/glycol based fluids have usually a lower viscosity then standard mineral hydraulic oils and this can seriously reduce the life expectancy of system components. Most pump manufacturers acknowledge this and either reduce maximum allowed operating pressures or warn you about shorter component life.

Has this system previously used standard hydraulic oil? If so, what were the differences in viscosity and Vickers vane pump ratings?

Another point to bear in mind is elastomer compatibility. Usually mineral oil compatible sealings are not compatible with glycol/water mixtures. This can lead to internal leakage, loss of pressure and wear.

 

[FLA]

Romke, very observant post

However true in the past, most pump manufacturers had been forced to cover themselves as water-glycol technology wasn't what it is today. The slight viscosity differential from a mineral oil fluids are negligible. Each batch (Mineral, synthetic, wg) will vary by slight amounts depending on the add-pack, baseoil viscosity used in the blends. The large bonus of water-glycols are that thye are synthetic in every sense of the word, that being said, they have a huge VI in comparison to any standard mineral oil on the market, therefore, during operation, the viscosity will not change at the same rate of a mineral oil and most systems will run better with less component degradation.

A good question asked is what the system contained before the wg fluid. If it was a mineral oil, and was flushed properly there should be no 'issue' in theory as the mineral oils wouldn't be significant enough to damage the new fluid. However, if there is a significant amount of mineral oil residue, it can wreak havoc on the fluid and in turn the system. Simple monthly (or more frequent) checks would be able to distinguish if there is residual min-oil causing the problems.

If the system was new even, you may want to check with the manufacturer of the system, to see how they test before shipping, in 90% of shops, unless specified a standard mineral oil is used as they are cheaper.

Seals/Elastomers:

Most 'newer' seal mediums will handle water-glycol fluids as the technologies have grown with the growing popularity of water glycol fluids. Unless you're using 'old' seals or something that is specifically not supposed to be used with water glycols all should be well.

Most suitable seal mediums are good for many different fluids, these are some recommended for use with water glycol fluids.

Suitable Elastomers
Fluorocarbon (Viton, Teflon)
Silicone (Silastic)
Fluorosilicone
PNF (phosphonitrilic fluoroelastomer)
Ethylene-Propylene
EPDM (ethylene-propylene diene terpolymer)
Natural Rubber (polyisoprene)
Butyl Rubber (isobutylene/isoprene)
Buna N (acrylonitrile-butadiene rubber, Nitrile, NBR)
Neoprene Rubber(Chloroprene)

These are NOT recommended.

Unsuitable Elastomers
Buna S (styrene-butadiene rubber, SBR)
Polyurethane
Epichlorohydrin
Other polar elastomers
Leather (dynamic seals)
Cork (dynamic seals)

If any further questions comments or concerns let me know.

 

What is the breakdown concerns of WG fluids. We have had components sent back to us with a sticky gel on them internally. Could this be glycol? caused by an chemical inbalance/breakdown. Most system operate at 130 deg. F. Could temperature cause this seperation or should we look at other things. Is there anything we should tell our customer or should we design the system to operate at a lower temp. If there is some where I could go to find this information please pass on.

 

[FLA]

Performanc,

Were there 'issues' with the fluid that caused your customer to sent those parts back to you in the first place, if so - what were they?

Once those components were taken from the system, the water could very well have evaporated off leaving a 'sticky film'. Is this film water soluble, does it wash off easily with water?

Water glycols don't break down persay, they can last much longer than a conventional mineral oil based fluid - assuming they're maintained properly <usually with the fluid manufacturers assistance> The general breakdown if any, is in the pressure and pump wear regions, i.e. if a glycol mixture breaks down you won't get the pump wear protection you're accustomed to, this should be noticable from the basic monthly testing that most manufacturers recommend and offer.

Hope it helps you some,

 

[LormarGuy]

STEELMAN, I hope that by now you performed a relatively affordable wear test called the 4 Ball Wear Test (ASTM D2266). It would have helped you confirm or reject the suppliers claims about lubricity. Way too many folks fail to maintain decent purity, viscosity and reserve alkalinity in their systems. Any varnishing present in pumps or servos?
Do you filter your new oil?
PERFORMANC, I saw an aluminum die caster reduce pump failures by about 40% by simply reducing operating temp. from 140 Deg. F. down to 100 Deg. F. with simple machine side coolers. Less evaporation is occuring which means less hassles for the operators that were constantly adjusting viscosity with demin water. Also they weren't maintaining the all-critical RESERVE ALKALINITY of the fluid consistently with supplier based buffers. Their pumps and servos also showed evidence of varnishing and GEL sludging. These problems were reduced by a combination of both temperature control, viscosity and RA control, and a periodic fluid reclamation/purification program. Hope this helps you both.