Phosphate  ester  fluid  conforming  to  specifi- cation MIL-H-19457 is used in aircraft elevators, ballast  valve  operating  systems,  and  replenish- ment-at-sea systems. This type of fluid contains a  controlled  amount  of  neurotoxic  material. Because of the neurotoxic effects that can result from  ingestion,  skin  absorption,  or  inhalation  of these  fluids,  be  sure  to  use  the  following precautions: 1.  Avoid  contact  with  the  fluids  by  wearing protective  clothing. 2.  Use  chemical  goggles  or  face  shields  to protect  your  eyes. 3.  If  you  are  expected  to  work  in  an atmosphere containing a fine mist or spray, wear a continuous-flow airline respirator. 4. Thoroughly clean skin areas contaminated by  this  fluid  with  soap  and  water. 5. If you get any fluid in your eyes, flush them with running water for at least 15 minutes and  seek  medical  attention. If  you  come  in  contact  with  MIL-H-19457 fluid, report the contact when you seek medical aid  and  whenever  you  have  a  routine  medical examination. Naval Ships’ Technical Manual, chapter 262, contains a list of protective clothing, along with national  stock  numbers  (NSN),  for  use  with  fluids conforming   to   MIL-H-19457.   It   also   contains procedures   for   repair   work   and   for   low-level leakage and massive spills cleanup. PHOSPHATE ESTER FLUID DISPOSAL.— Waste MIL-H-19457 fluids and refuse (rags and other materials) must not be dumped at sea. Fluid should be placed in bung-type drums. Rags and other  materials  should  be  placed  in  open  top drums for shore disposal. These drums should be marked with a warning label stating their content, safety   precautions,   and   disposal   instructions. Detailed  instructions  for  phosphate  ester  fluids disposal can be found in  Naval  Ships’  Technical Manual, chapter  262,  and  OPNAVINST  5090.1. Silicone  Synthetic  Fire-Resistant  Fluids Silicone   synthetic   fire-resistant   fluids   are frequently   used   for   hydraulic   systems   which require   fire   resistance,   but   which   have   only marginal   requirements   for   other   chemical   or physical  properties  common  to  hydraulic  fluids. Silicone  fluids  do  not  have  the  detrimental characteristics   of   phosphate   ester   fluids,   nor do   they   provide   the   corrosion   protection   and lubrication  of  phosphate  ester  fluids,  but  they  are excellent  for  fire  protection.  Silicone  fluid conforming to MIL-S-81087 is used in the missile holddown  and  lockout  system  aboard  submarines. Lightweight  Synthetic  Fire-Resistant  Fluids In   applications   where   weight   is   critical, lightweight  synthetic  fluid  is  used  in  hydraulic systems. MIL-H-83282 is a synthetic, fire-resistant hydraulic   fluid   used   in   military   aircraft   and hydrofoils  where  the  requirement  to  minimize weight  dictates  the  use  of  a  low-viscosity  fluid. It is also the most commonly used fluid in aviation support  equipment.  NAVAIR  01-1A-17  contains additional  information  on  fluids  conforming  to specification   MIL-H-83282. WATER-BASED  FIRE-RESISTANT FLUIDS The most widely used water-based hydraulic fluids may be classified as water-glycol mixtures and  water-synthetic  base  mixtures.  The  water- glycol mixture contains additives to protect it from oxidation,  corrosion,  and  biological  growth  and to  enhance  its  load-carrying  capacity. Fire  resistance  of  the  water  mixture  fluids depends   on   the   vaporization   and   smothering effect  of  steam  generated  from  the  water.  The water  in  water-based  fluids  is  constantly  being driven off while the system is operating. There- fore,  frequent  checks  to  maintain  the  correct  ratio of  water  are  important. The   water-based   fluid   used   in   catapult retracting   engines,   jet   blast   deflectors,   and weapons  elevators  and  handling  systems  conforms to   MIL-H-22072. The  safety  precautions  outlined  for  phosphate ester  fluid  and  the  disposal  of  phosphate  ester fluid also apply to water-based fluid conforming to   MIL-H-22072. CONTAMINATION Hydraulic   fluid   contamination   may   be described  as  any  foreign  material  or  substance whose presence in the fluid is capable of adversely affecting  system  performance  or  reliability.  It  may assume many different forms, including liquids, gases,  and  solid  matter  of  various  composition, sizes, and shapes. Solid matter is the type most often found in hydraulic systems and is generally 3-6