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ST-55 fluid, part numbers and information

The P3100/P3200 deadweight tester user manual refers to ST-55 fluid as "Shell Spindle Oil 22, our reference 55-655." We more commonly refer to it as ST-55 oil. Historically it has also been called Tellus 22, Morlina S2 or EL 22 or Fluid 22.

ST-55 is almost always used with liquid deadweight testers, especially current models. Density is 879 kg/m3. Viscosity is 55 cSt at 20C, 22 cSt at 40C. Surface tension is 0.0283 N/m

Part Number: 3905893
Description: ST-55 Operating Fluid (Oil), Quart
Price: Send by email
Notes: 1 quart is equal to 0.95 liter. The reservoir of a P3100 deadweight tester has a usable volume of about 400 cubic centimeters (25 cubic inches), or about 0.4 liters or 13.5 US fluid ounces or 0.4 US quart. 

MSDS sheet is here,
EL DWT Fluid-22 (ST-55, 55-655, PA9152, DW6293) 

Sample certificate of analysis link is below that shows shelf life of 4-years.

Fill date and lot number are shown on  label. Recent certificates of analysis are available by download links below. If not shown below please use the link below to request this.


Official information, quotations and terms and conditions can be obtained from our Orders group at 1.877.355.3225 or

Purchase order may be faxed to 1.425.446.5716 or emailed to

Credit card orders can be made by phone by calling 1.877.355.3225

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