Flushing Fluid MultiTherm FF-1®

The Logical First Step in Heat Transfer System Start-Up!

MultiTherm FF-1® flushing fluid is for use in start-up or general maintenance of heat transfer fluid systems. During new equipment start-up, it is an economical way to remove loose material such as weld splatter, fines, particulate matter, etc. left in lines and equipment, along with oil and some preservative coatings. It is useful for general maintenance purposes for removing particulate matter and used heat transfer fluid from a system prior to recharge or changeover from one fluid to another.

MultiTherm FF-1® flushing fluid is formulated to be compatible with MultiTherm® and most other heat transfer fluids so that small residual amounts left in equipment will not be a problem.

System Preparation
New systems may contain mill scale, weld splatter, slag, flux, quench oil, protective coatings, dirt and water. The abrasive contamination can damage pump seals, bearings, and control valves. Mill scale and weld splatter can promote fluid oxidation and cracking. The oil, coatings and flux are thermally unstable and can cause fluid degradation.

Some say to leave the system as is, and explain that buying replacement fluid a little earlier is cheaper than the cost of cleanout. However, the cost of mechanical seal replacement and control valve rebuilds probably exceed the cleanout cost. When the expense of unscheduled downtime is added, the cost of professional cleanout is usually justified.

Removing mill scale, oil and coatings from all pipe sections and fittings before installation can avoid problems. Use Robvon or equal back-up rings at each weldment. Clean and dry out the heater and all heat users before installation.

It is strongly recommended that water not be used for cleanout of an assembled system or for “hydro” pressure testing. Water in a hot oil system will cause pump cavitation and can easily ruin pump seals and bearings. Trapped in a dead leg and hit by high-temperature fluid, water can literally blow up the pipe, or the expansion can push hot fluid from a vent, possibly jeopardizing personnel. To pressure test a system, use either MultiTherm FF-1® flushing fluid or heat transfer fluid or inert gas in lieu of water. Pressurize fluid with nitrogen, not air.

Maximum Use Temperature
Open System 225°F
Closed System Up to 600°F for several days only. Use nitrogen blanket or cold seal/thermal Buffer tank connected to expansion tank.

Typical Properties
Base Oil Light Distillate
Appearance Clear, pale straw to water white
Odor Slight oily
Specific Gravity @ 59°F (15°C) 0.910
Density, lb/gal @ 59°F (15°C) 7.578 lb/gal
3.437 kg/gal
Pour Point, ASTM D97 -40°F
Flash Point, coc, ASTM D92 320°F
Autoignition Temp, Estimated 650°F
Initial Boiling Point, ASTM D1160 520°F
Viscosity, SUS, @ 100°F (38°C) 110
Pumpable, Centrifugal @ 465 cP 32°F
Average Molecular Weight 305

System Filling
If a system has been flushed, cleaned or pressure tested with water, blow out residual water, ideally with nitrogen. Then add MultiTherm FF-1® flushing fluid.

Slowly pump the fluid into the system from the bottom up to vent air. Fillingfrom the top (pouring into the expansion tank) hinders air venting and needlessly aerates the fluid. Air in the fluid can lead to pump cavitation and fluid oxidation. Often, a convenient place to fill is through the blow down connection on the strainer. Use a small positive displacement pump to transfer fluid rather than the system pump.

Particulate Removal
Circulate fluid at room temperature. When circulating pump suction pressure drops to zero or a negative number, clean the filter. Continue to repeat this procedure until suction pressure stays at the normal positive reading. Typical filters are 60-mesh stainless steel, however, some pump manufactures recommend 100-mesh to protect seals.

Water Removal
The more complex the system, the more difficult the water removal will be. One method is to locate the valve nearest to the system’s low point and drain a small quantity of cold fluid into a beaker and allow it to stand for several minutes. If you notice a phase separation (fluid floating on top of the water), keep sampling until you draw pure fluid. Start the system’s pump, shut down, allow the system to stand, and repeat the sampling procedure. Do this until no water is observed in the beaker.

Now, bring the system up to about 180°F and heat very slow to 225°F (above the boiling point of water, but below the fluid’s oxidation point). While the system is heating to 180°F, open expansion tank warm-up valve to include the tank in the loop. Water vapor from the outside air will often condense in the tank. Open the vent to allow the water to “steam” off. Be sure to close both valves and properly hook up the inert gas blanket or cold seal tank once all water is exhausted from the system. Continue to run the system until the vent stops “steaming”.

After the water has been boiled out, heat the system slowly to a maximum of 500°F. Continue to watch pump suction pressure and if it falls to zero or a negative number, clean out the filter. At elevated temperatures more protective costing material may be removed, weld splatter and scale loosened and dirt produced. During the start-up of a new system, filters may require cleaning 3 to 20 times over a two day period. Turn off the heat and allow the pump to run until the MultiTherm FF-1® flushing fluid is cool enough to dump safely. With some systems, safe dumping can be accomplished at 225°F while others may require lowering temperature to 150°F. Clean the filter once again before charging with heat transfer fluid.

General Maintenance
MultiTherm FF-1® flushing fluid is useful to remove particulate contamination and for flushing a system when changing heat transfer fluids. Generally follow the above instructions so that the expansion tank is also flushed and check for water from condensation to be safe.

Please Note
MultiTherm FF-1® is not a cleaner. It cannot be expected to remove all tightly bonded carbonaceous varnish or “cokedon material” that can form during operation or well-bonded preservative coatings. Where any severe dirt or fouling problem occurs.

Warranty: MultiTherm® warrants that MultiTherm FF-1® conforms to the data set forth in this brochure. We present this information in good faith, but because we cannot control or anticipate the many different conditions under which our information and product may be used, no other warranty, expressed or implied, is given.