Bath Fluids

Finally, there’s a convenient source for small quantities of bath fluids for any temperature range. Why pay for more than you need?

Hart Scientific carries a full line of bath fluids covering temperature ranges from –100°C to 550°C.

Viscosity, volatility and other properties that change with temperature affect the performance of fluids in controlled baths and circulators. Hart has tested and used each of the fluids we sell. Over the ranges recommended in the following table, each fluid remains at a low enough viscosity to be adequately pumped or stirred. Whether your application is industrial or critical lab calibration work, Hart fluids give you top performance and stability.

For temperature ranges too high for oils, we have a bath salt with a viscosity in the molten state similar to the viscosity of water. For your convenience, it is shipped in a granular form, making it easy to fill your bath.

Between its melting point of 150°C and 550°C, this salt has the highest temperature stability and uniformity available in a bath fluid. It does not smoke like oils or give off dust like “sand” or fluidized alumina baths. Check with your bath manufacturer before using this salt to make sure your equipment is compatible. Hart offers three standard bath models and custom-designed units for use with this salt.

Fluid Specifications

It’s important to understand a few specifications before selecting a bath fluid. We’ve seen bath fluids advertised with a temperature range that spans from the freezing point to the flash point or beyond.

For example, type 710 silicone oil has a freezing point of –22°C, but freezing point has nothing to do with the point at which the oil becomes so thick it cannot be properly stirred. Type 710 oil should really only be used down to about 80°C. It’s a viscosity issue, not a freezing-point issue. Usable range is the question. Suitability for calibration work is the specification that counts.

The usable viscosity range is determined by your bath’s stirring or pumping design. Hart baths can be operated using fluids with up to 50 centistokes viscosity. This gives you additional usable range in the lower temperature levels of the fluid.

Some baths advertised as calibration baths require fluids with 10 centistokes or less viscosity to operate properly. The usable ranges in our table on the previous page assume the use of a Hart bath.

In addition to range and viscosity issues, there are a number of other issues to consider when choosing a bath fluid. The other considerations are:

Thermal characteristics
Lifetime
Change in characteristics due to temperature cycling
Absorption of water from the air
Vaporization—fumes and fume hood requirements
Expansion due to heat
Contamination—mixing oils or introducing contamination with unclean probes
Conductivity properties
Effects of using fluids outside of their range—fire, explosion, polymerization
Effects of altitude on boiling point

Fluid	Usable Range^§	Flash Point^†	Model #	Material Safety Data Sheets⁽¹⁾
Halocarbon 0.8 Cold Bath Fluid	–100°C to 70°C	n/a	5019	halocarb.pdf (24 KB)
HFE Cold Bath Fluid	–75°C to 100°C	n/a	5023	hfe7500.pdf (42 KB)
Dynalene HF/LO*	–65°C to 58°C	60°C	5022	dynalene.pdf (167 KB)
Ethylene Glycol (Mix 1:1 with water)	–30°C to 90°C	n/a	5020	ethgly.pdf (19 KB)
Silicone Oil Type 200.05	–40°C to 130°C	133°C	5010	dw200-05.pdf (50 KB)
Silicone Oil Type 200.10	–30°C to 160°C	163°C	5012	dw200-10.pdf (49 KB)
Silicone Oil Type 200.20	10°C to 230°C	232°C	5013	dw200-20.pdf (50 KB)
Silicone Oil Type 200.50	30°C to 278°C	280°C	5014	dw200-50.pdf (50 KB)
Silicone Oil Type 210H		175°C	5024	210h_fluid.pdf (46 KB)
Silicone Oil Type 550	70°C to 228°C	230°C	5016	dw550.pdf (42 KB)
Silicone Oil Type 710	80°C to 300°C	302°C	5017	dw710.pdf (46 KB)
Mineral Oil	10°C to 175°C	177°C	5011	minoil.pdf (452 KB)
Bath Salt, 125 lb.^‡ Potassium Nitrate 53% Sodium Nitrite 40% Sodium Nitrate 7%	180°C to 550°C	n/a	5001	heatsalt.pdf (257 KB) heatsalt_ansi.pdf (44 KB)
^§Atmospheric pressure affects the usable ranges of some fluids. The temperatures quoted are at sea level. ^†Flash point is the temperature at which a vapor (not the fluid) will ignite if exposed to an open flame. When the flame is removed, the vapor will stop burning. (Open cup method.) *Electrical resistivity is greater than 20 MW-cm. ^‡125 lb. bath salt fills a 7.9-gallon tank.
⁽¹⁾The MSDS available are in Adobe Acrobat format and require the Acrobat Reader to view. If you need a reader go to Adobe's Web Site to download the appropriate reader for your system. The MSDS may be downloaded rather than viewed online by right clicking on the link and in Microsoft Internet Explorer clicking on “Save Target As...” or in Netscape “Save Link As...” or alternatively going to ftp.hartscientific.com/msds.

Click to request a quote, catalog, or other literature. Or call us at 1-800-438-4278.

Home | What's New | Products | Support | U.S. Cal Lab | European Cal Lab | Accreditation |Training | Events | Publications |Contact Hart | International | Links | Fun Stuff | Software | Contents