LST Fastfloat heavy liquid FAQ

Questions & Answers: LST Fastfloat

Is there an SDS (Material Safety Data Sheet) available for LST Fastfloat?
Yes, we can provide an SDS on request. We also supply an SDS with every order.

What is the chemical composition of LST Fastfloat?
LST Fastfloat contains hydrated sodium heteropolytungstates (80 wt%) in water.

Is the vapor pressure of LST Fastfloat at room temperature the same as that for water?
The vapour pressure of water above LST Fastfloat (SG 2.80) is slightly lower than the vapour pressure of water above pure water. This is typical of many inorganic salts in water.

My LST Fastfloat has turned dark blue / grey / black. What causes this, is the LST Fastfloat damaged, and how can I get the heavy liquid back to its original state?
The blue colouration is a well known chemical reaction which polytungstates and heteropolytungstates can undergo when chemically reduced, i.e. when the heavy liquid gains electrons from a metal or other similar reducing agent. At high temperatures, such as might occur if the heavy liquid crystallised on a hotplate, even carbon, dust or dirt can sometimes act as a reducing agent. It occurs most commonly when the heavy liquid is contaminated by contact with iron.

The easiest way to remove the dark blue colour is to add a few drops of 30% hydrogen peroxide solution (H2O2) to re-oxidise the heavy liquid. Normally no more than 1 mL of 30% H2O2 should be added to every 200 mL of affected LST Fastfloat. The discoloured heavy liquid and hydrogen peroxide is then warmed to about 80-90 °C to remove the colour. It is normal for the heavy liquid to effervesce during the process.

To remove the colour from large quantities of heavy liquid, especially to remove the dark brown which is caused by accumulated soluble iron species, full strength LST Fastfloat can be pumped through a clean “activated carbon” water cartridge. It is important that the activated carbon cartridge is well washed so it does not release carbon particles into the LST Fastfloat.

Is there any form of reactivity with polyester or other plastic materials?
LST Fastfloat does not react with most plastic materials. For example polyethylene, polypropylene, PVC, and TPX have proven their compatibility when used on a daily basis with LST Fastfloat. Some nylon materials can be affected by the slight acidity (~pH 4) of the heavy liquid. Please contact us if you are not sure about the compatibility of a material.

Does freezing affect LST Fastfloat?
Freezing is reversible, just like it is with water and ice. Extreme cold will cause the LST Fastfloat to crystallise, but will not affect the chemical components. Applying warmth (for example, 50 °C) over several hours or overnight will re-form the heavy liquid. It is faster if you stir the liquid and crystals while warming the crystallised LST Fastfloat.

How sensitive is the density of LST Fastfloat to changes in room temperature?
In the absence of crystallisation or evaporation, the density of LST Fastfloat varies very little with temperature. The density of the heavy liquid changes by approximately 0.01 g/ml for a 10 °C temperature change.

Evaporation or crystallisation can significantly affect the density of LST Fastfloat. For example, if LST Fastfloat is left open in a draft, such as in a fume cupboard, then evaporation can cause the density to change. Also, if the laboratory temperature cools to below 20 °C overnight or during work, crystallisation may occur which decreases the density of the liquid above the crystals.

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