Hydraulic Fluid and Method of Preventing Vapor Phase Corrosion

Abstract

A metal glycol-based hydraulic fluid having vapor phase corrosion inhibition properties is disclosed. The hydraulic fluid can be used in food related applications.

1 . A hydraulic fluid comprising:
 (a) about 25% to about 50%, by weight, of a glycol;   (b) about 0.5% to about 8%, by weight, of a partially neutralized aliphatic C 6 -C 16  carboxylic acid;   (c) about 15% to about 40%, by weight, of a polyalkylene glycol;   (d) 0.05% to about 1%, by weight, of an ammonium salt;   (e) a sufficient amount of a buffering alkali to provide a reserve alkalinity of at least about 20 ml;   (f) about 0% to about 0.5%, by weight, in total, of one or more of a defoamer, a dye, and a metal deactivator; and   (g) about 25% to about 50%, by weight, water.   
   
   
       2 . The fluid of  claim 1  wherein the glycol is selected from the group consisting of ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, diethylene glycol, dipropylene glycol, dihexylene glycol, triethylene glycol, tripropylene glycol, trihexylene glycol, and mixtures thereof. 
   
   
       3 . The fluid of  claim 1  wherein the C 6 -C 16  carboxylic acid comprises one of more of hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, undecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, tridecanoic acid, 2-ethylhexanoic acid, and 2-propylhexanoic acid. 
   
   
       4 . The fluid of  claim 1  wherein the C 6 -C 16  carboxylic acid is neutralized at least 50% to less than 100%. 
   
   
       5 . The fluid of  claim 1  wherein the polyalkylene glycol comprises a polyethylene glycol, a polypropylene glycol, an ethylene oxide-propylene oxide copolymer, or a mixture thereof. 
   
   
       6 . The fluid of  claim 1  wherein the polyalkylene glycol has a molecular weight of least about 5000 and up to about 200,000. 
   
   
       7 . The fluid of  claim 1  wherein the polyalkylene glycol comprises a methyl-oxirane polymer. 
   
   
       8 . The fluid of  claim 1  wherein the ammonium salt is one or more of ammonium carbonate, ammonium hydroxide, and ammonium acetate. 
   
   
       9 . The fluid of  claim 1  wherein the buffering alkali is selected from the group consisting of a carbonate, a bicarbonate, a borate, a tetraborate, a phosphate, and mixtures thereof. 
   
   
       10 . A method of transmitting power or carrying a load comprising subjecting a hydraulic fluid of  claim 1  to pressure. 
   
   
       11 . A method of  claim 9  wherein the power is transmitting or a load is carried in a food processing facility, a food preparation facility, or a food serving facility. 
   
   
       12 . A method of inhibiting, retarding, or preventing vapor phase corrosion of an exposed metal surface caused by a hydraulic fluid comprising incorporating an effective amount of an ammonium salt in a water/glycol-based hydraulic fluid. 
   
   
       13 . The method of  claim 12  wherein the water/glycol-based hydraulic fluid comprises about 0.5% to about 1%, by weight, of the ammonium salt. 
   
   
       14 . The method of  claim 12  wherein the water/glycol-based hydraulic fluid comprises:
 (a) about 25% to about 50%, by weight, of a glycol;   (b) about 0.5% to about 8%, by weight, of a partially neutralized aliphatic C 6 -C 16  carboxylic acid;   (c) about 15% to about 40%, by weight, of a polyalkylene glycol;   (d) 0.05% to about 1%, by weight, of an ammonium salt;   (e) a sufficient amount of a buffering alkali to provide a reserve alkalinity of at least about 20 ml;   (f) about 0% to about 0.5%, by weight, in total, of one or more of a defoamer, a dye, and a metal deactivator; and   (g) about 25% to about 50%, by weight, water.