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Firstly, what sort of heat do you have? Conduction, convection or radiated heat?

We are often asked for a solution to a heat problem and the first thing we think about is whether the problem is caused by conduction, convection or radiation.

We will try to keep this simple.

  • Conduction is the transfer of heat energy by direct contact.
  • Convection is caused by heat transfer within a fluid (includes liquids and gases etc.)
  • Radiation is when heat is transferred without any physical contact (ie Sun rays)

The actual answer is usually a combination of all three, but one heat transfer method is usually the dominant factor.

Conduction

Conduction is the direct transfer of heat through matter caused by the temperature differential between the two objects. If we have a cast iron exhaust manifold and we attach an aluminium heat shield directly to that manifold, the heat energy will flow into the aluminium heat shield until they are approximately the same temperature.

In this example, the heat shield is ineffective.

To protect something from heat conduction, we need to put a barrier between the hot object and the object we are trying to keep cool.

For instance, we could mount our aluminium heat shield any distance away from the hot exhaust manifold with spacers. The heat shield now feels zero conducted heat, but will still feel radiated heat.

Another example of this would be placing your hand against a hot oven glass door. You would probably burn your hand. Move your hand away from the door by 20mm and although you would still feel radiated heat, there would be no more conduction.

Then place an aluminium panel half way between the hot glass oven door and your hand and you will feel very little heat. The aluminium panel has blocked radiated heat.

Convection

As mentioned above, convection is heat transfer by actual movement of matter through a fluid. In this definition fluids include liquids and gases.

An electric fan heater is a good example of convection. The fan forces air to flow over a hot electrical element. The air is heated by the element and then blown out into the room.

Another example is a car radiator. Water flows through an engine and is heated by the hot engine block. This heated water is pumped through the radiator. The radiator is cooled by the flow of cold air through the front of the car. The hot water flows through the cool radiator and heat transfers from the water to the radiator. The warming radiator then passes that transferred heat back to the air as it flows through the radiator.

In the heat protection industry, we may choose to divert the flow of hot fluids (air or water) away from the object that we are trying to keep cool.

Radiation

Radiation occurs where heat is transferred as electromagnetic waves. If you hold your hand up to the sun, or next to a hot exhaust manifold (ignoring air flow) you will feel the radiant energy coming from the sun or hot object.

We can protect items from radiant heat by placing a barrier between the radiant heat source and the item we want to protect.

The Art of Insulation

Our job at Kool Wrap is to project operators and heat sensitive components from heat transferred by Conduction, Convection and Radiation.

One of the most used insulators is actually air.

If we consider roof insulation, we use a variety of products such as fibreglass batts to create a layer of trapped air pockets.

The technical reason why air is a poor conductor of heat is that the air molecules are not in continuous contact with each other. The air pockets in fibreglass or bubble wrap insulation, cannot move around and transfer heat.

Remember that heat will only transfer to something that is cooler. If the heated air is prevented from touching cooler air, then the heat cannot be transferred. If we are using the ceiling insulation example, in summer, the heated air inside your roof, cannot transfer heat through the insulation.

In an industrial or automotive setting, we can use fibreglass tape or lagging to wrap around an exhaust pipe and that tape will contain thousands of tiny air pockets that can help prevent the heat transfer process.

If you have questions about your heat transfer problems, call Kool Wrap today and we will help you to find a solution.

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Should My Exhaust Wrap or New Turbo Blanket Smoke on First Start-Up

Kool Wrap exhaust wrap with smoke

The short answer is yes. Most fibreglass and basalt insulation products will emit some smoke during their first heat cycle.

During the production process for glass fibre fabrics, binders or specially formulated starches are used to lubricate the fibres and hold them in their woven pattern.

Kool Wrap exhaust wrap with smoke

When subject to high temperatures these starches or binders can evaporate or burn off causing smoke to be emitted by the fibreglass tapes or fabrics. This causes no damage and is quite normal although it can be a little scary if you are not expecting it.

The smoking will not last long as is simply a normal occurence.

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Is your hot oven damaging your kitchen cabinetry?

We have had some phone calls recently from customers that have experienced heat damage to their kitchen cabinets caused by a hot oven.

One customer said “My under bench 90cm Whirlpool oven (2 yrs old) is burning the cabinet which is to the left of it. The vinyl wrap has warped and there is a permanent yellow stain”.

Oven heat damaged kitchen cupboards

There are a combination of factors that can cause an oven’s excess heat to damage to your kitchen cupboards and cabinets.

Insufficient air gap between the oven and the cabinets:

  • Insufficient air gap between the oven and the cabinets
  • Insufficient air ventilation between the oven and the cabinets
  • Insufficient heat insulation within the ovens casing or body
  • Heat sensitive cabinet coatings such as vinyl wrapped cabinetry

Kool Wrap is a specialist heat protection products company and we have developed a heat insulation kit that can help protect your valuable kitchen.

The Kool Wrap Oven Cavity Heat Protection Kit consists of 2 sheets of heat insulating fibreglass with a self adhesive layer on the back. Simply peel off the back paper and stick to the left and right sides of the oven cavity.

Kool Wrap Oven Cavity Insulation Kit

The sheets also have an outer layer of heat reflective aluminium foil to reflect damaging heat radiation back away from your cabinetry. This foil can withstand temperatures up to 660°C, far higher than a typical oven.

The sheet material can be cut with scissors and should take no more than 5-10 minutes to install.

Click HERE to view the kit.

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What Is Basalt or Lava Rock Exhaust Wrap

Kool Wrap Basalt Titanium Exhaust Heat Wrap

Wrapping super hot engine exhaust pipes in a high temperature resistant insulating tape has become more popular recently for a number of reasons.

  1. Hot exhaust pipes can be a safety hazard to workers and mechanics working on or using the equipment.
  2. The hot exhaust can be a fire risk. In mines or in agriculture dust or chaff can gather on the hot exhausts or mufflers causing fires. We were told that up to 10% of all combine harvesters catch fire every year!
  3. Keeping the heat inside an exhaust pipe helps to keep the exhaust traveling quickly through the exhaust pipe making the engine run more efficiently.
  4. Exhaust wrap can reduce working temperatures in the vicinity.

Kool Wrap Titanium Exhaust Wrap

Kool Wrap manufacturers a range of wraps with the Basalt Titanium Wrap being the highest quality wrap in the range.

Remarkably, Basalt (often known as Lava Rock) is produced by melting down carefully chosen rock formations that are the result of volcanic activity. The molten rock is then forced through an extruding machine to produce very fine strands of glass fibre that are then woven into various products.  These strands have a filament diameter of 10-20um which is far enough above the respiratory limit of 5um to make it suitable replacement for asbestos.

Basalt fibers are known to be 25% stronger than regular glass fibers and are often used in producing composites that are very similar to carbon fibre.

Wikipedia also quotes, Basalt Fibres “……….also have a high elastic modulus, resulting in excellent specific strength—three times that of steel. Thin fiber is usually used for textile applications mainly for production of woven fabric. Thicker fiber is used in filament winding, for example, for production of CNG cylinders or pipes. The thickest fiber is used for pultrusion, geogrid, UD, multiaxial fabric production and in form of chopped strand for concrete reinforcement. One of the most prospective applications for continuous basalt fiber and the most modern trend at the moment is production of basalt rebar that more and more substitutes traditional steel rebar on construction market.

 

 

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How Hot Does My Exhaust Get?

Formula 1 engine red hot

In short, the highest temperatures that an exhaust manifold or exhaust pipe should ever reach would be approximately 850°C (1,600°F). As a guide, metals will start to turn red at 500°C and be a dark cherry red at around 635°C (1,175°F).

The hottest parts of your exhaust system will be either a bend in an exhaust pipe right next to the cylinder hard or around the catalytic converter.

Temperatures naturally increase as RPM or the engine work load increases. This is when the engine is consuming the maximum amount of fuel and producing the most amount of torque or horsepower.

Tests on the exhaust system temperatures of typical road cars ranged from 120°C (250°F) at 50kph (30mph) up to 550°C (1,020°F) at 112kph (70mph).

Red Hot Motorcycle exhuast pipe

There are 3 ways to prevent damage to nearby components under the above conditions:

  • Insulate the exhaust pipe to keep the heat inside the pipe
  • Place a reflecting barrier with an air gap between the exhaust pipe and the rest of the engine bay and its components
  • Add reflective and insulating materials to objects that could be damaged by the radiant heat coming from the exhaust pipes or manifold.

We typically use exhaust wraps or tapes and wrap these in spiral pattern around the exhaust pipe or manifold to keep the heat inside the pipes. Tests have shown that exhaust wrap can reduce engine bay temperatures by as much as 50%. These exhaust wraps can be made from fibreglass (starts to melt at 815°C), silica, basalt and ceramic wraps.

Car manufacturers have also caught on to the importance of heat control and most late model cars have embossed aluminium or steel heat shields. These are usually mounted in fresh air approximately 1-2 cm away from the exhaust or exhaust manifold. This air gap helps to carry away excess heat.

Heat sleeves are also now used in many new car engine bays to reduce the chances of heat damage to cables, wiring, hoses and hard lines. These sleeves are usually a lamination of aluminium foil and an insulating fibreglass backing. These sleeves use the reflective ability of reflective aluminium foil to repel radiant heat. The fibreglass backing gives the sleeve strength but also acts as an insulator.

Some heat sleeves use a mylar foil outer layer. Mylar is made from a microscopic layer of foil laminated to an outer layer of polyester resin. This is usually backed with an insulating layer of fibreglass. The polyester outer layer makes Mylar really tough, but it will burn off at around 200°C (400°F). Kool Wrap uses a thicker outer aluminium foil backed by insulating fibreglass. This material is available as a sleeve or in sheet form so that it can be used to insulate car components such as a starter motors or a firewall. The Kool Wrap foil and fibreglass can withstand temperatures approaching 660°C (1,220°F).

Remember that air is actually a great insulator when trapped in small pockets. Air is excellent at convection (electric fan heater) but is a poor conductor of heat due to its low mass. You can see evidence of this in styrene foam or ceiling insulating batts. These two products are designed to trap air pockets and reduce heat conduction. The material acts as a heat block. The heat cannot be transferred through the material. The same applies to exhaust wraps and fibreglass or silica blankets or wraps. The air trapped between the fibres reduces heat conduction.

A good example of trapped air acting as a heat barrier is double glazed windows.

References:

University of Washington: Underhood Surface Temperature Tests: Summary of Published Results

https://depts.washington.edu/vehfire/ignition/autoignition/surftemper.html

 

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How To Install Our Latest Kool Wrap Exhaust Wrap Insulation

First, you need to work out how much of our Kool Wrap exhaust wrap do you need.

If you are wrapping smaller diameter pipes up to 37mm (1.5”), use a 25mm wide wrap. If your pipes are larger than 377mm in diameter then choose the 50mm (2”) wide wraps.

A Harley Davidson has larger primary pipes and will typically use 15m of wrap. A 4-cylinder engine will also use 15m while a V8 will require 2 15m rolls.Kool Wrap Titanium Exhaust Wrap on headers

Koolwrap offers its standard range fibreglass insulation wraps in white, natural (cream or tan) and black. If you are racing, then your pipes can easily get red hot and we would then recommend our high temp range of either a Vermiculte coated fibreglass wrap or our Titanium wraps. Our Titanium wraps will withstand up continuous exposure up to 1,800°F or 980°C. The melting point is a sky high 2,500°F or 980°C.

You do not have to dampen your Kool Wrap exhaust wrap before applying as our latest high-tech wraps are more flexible than older style wraps and confirm well to corners.

However, there is no harm dampening the wraps if you choose to. It may help to get a tighter finish and can help reduce the small fibres that come off the wraps and can cause skin irritation. Always use gloves and long sleeves when applying. If you decide to dampen your Kool Wrap exhaust wrap, do not soak the wrap in a bucket. Simply dampen the wrap under a tap or use a spray bottle.

It is easier if you work out approximately how much wrap you will need for each pipe before you start and cut a separate length of wrap for each pipe. This avoids trying to pass a large roll of wrap around the pipes.

Fold over the first 15cm of wrap to avoid a fraying end and to provide a tidy start. Then overlap the first 1-2 wraps to lock it on place. You can also add a stainless steel tie at this point to firmly hold your starting point. Then wrap slowly around the pipes using 5-8mm overlap (1/4”). The overlap will naturally increase on the inside of the bends. Keep tension on the wrap to give a nice tight finish.

You can finish your wrap with a spray paint aerosol can. You could choose a clear or a colour of your choice. This will help to lock down any loose fibres and help prevent liquids and dirt from staining your wrap.

You will initially notice the wrap will smoke when you first start your engine. This will disappear after 15-30 mins.

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Formula 1 Exhaust Wrap

F1 Exhaust wrap heat protection
F1 Exhaust wrap heat protection

We are big Formula 1 fans here at Kool Wrap and we were delighted to see Daniel Ricciardo win the Chinese Grand Prix last week.

The Formula 1 teams are notoriously secretive and we rarely see behind the scenes photos of their technology. But we recently came across this photo of an unidentified Formula 1 engine from winter testing and you can easily see that they have used exhaust wraps or shielding to contain exhaust heat temperatures.

Heat management is extremely important in F1. Air intakes for intercoolers, radiators and oil coolers need to be kept to a minimum as they create aerodynamic drag and cost valuable lap time.

Racing has always been a fantastic test bed for new technology. Many previous inventions find there way onto our roadcars such as disc brakes, seat belts and fuel injection.

Today’s Formula 1 engines have reached amazing new levels of efficiency.  If we look at the energy stored in racing fuel (I will not go into how energy is never created, it is just transformed from one place to another) the engine designers job is to convert as much of that stored energy into twisting power. Petrol engines have always been fairly inefficient. When we convert petrol into heat, some of that energy pushes down the piston to turn the crank, but most of that heat energy disappears out of the exhaust pipe or into the cooling system.

A typical petrol engine in a late model car has an efficiency score of around 20%. That means 80% of the thermal efficiency is lost in exhaust gas, friction etc.

Mercedes F1 announced late last year that they have exceeded 50% thermal efficiency. This helps to explain how they can make 900+hp from a 1.6 litre V6 engine!

Advances in heat management have contributed to these efficiency gains. Mercedes have tried to keep as much heat energy inside the exhaust pipes so that it can drive their turbocharger to both create turbo boost pressure but to also generate electricity that can power their hybrid systems.

We will leave Formula 1 engine technology discussions for another blog later this year, but we can expect to see standard roadcars of the future doing a far better job of converting fuel into usable energy.

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Do Turbo Blankets Actually Boost Performance?

Kool Wrap T4 Titanium Turbo Blanket

Kool Wrap Black Silicone Coated Turbo Blanket

Turbo Blankets or Beanies where introduced for 4 key reasons:

  • Reduce under bonnet or hood temperatures to protect fuel lines, hoses and other engine components from heat damage
  • Reduce the chance of injury for mechanics working near hot turbochargers
  • Improve performance by lowering engine bay temperatures and therefore intake air temperatures
  • Increase temperatures of the turbo exhaust housing and therefore accelerate the intake turbine faster, reducing lag and in turn increase boost pressures

Turbo Blankets have no doubt proved themselves to be very popular with turbo car owners, but will a Turbo Blanket really bring on Boost faster?

Luckily for us, graduate research assistant Steffen Bickle at the University of Texas decided to thoroughly investigate this theory.

Click HERE to read his paper.

The short version is, yes, Turbo Blankets or Turbo Beanies definitely do increase exhaust housing temperatures and help to build boost faster.

Steffan Bickle found that …..”With the turbo blanket mounted, the turbocharger shaft speeds exceeded their baseline counterpart for identical engine operating conditions which resulted in increased boost pressures throughout all tested steady state speed-load point”.

He went on to conclude…”The time-to-torque improvement with the PTP Turbo Blanket was significant, especially for the last case, in which we used a simultaneous tip-in of the speed and the load, the time-to-torque improvement was impressive with an instantaneous torque improvement of up to 140 Nm. This led to an acceleration advantage of 250 engine rpm in spite of the fact that the duration was less than 2.5 s for the entire event. The improvement of the turbocharger performance provided this engine performance advantage because the turbocharger spool-up was faster which resulted in a boost pressure advantage of up to 0.3 bar when the PTP Turbo Blanket was mounted”.

I think that we can safely agree that a Turbo Beanie or Turbo Blanket is a very cheap and easy addition to any Turbocharged Car and the benefits are proven.

  • Faster spool up of the turbocharger- less lag
  • Cooler under bonnet or under hood temperatures
  • Potential power gains by reduced engine bay temperatures
  • A safer engine bay for mechanics and enthusiasts

Check our the Kool Wrap range of Turbo Blankets or Beanies

 

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Industrial Heat Protection

Heat exhaustion

Most workers feel comfortable and therefore work efficiently when the air temperature is between 20°C (68°F) and 27°C ( 80°F) and relative humidity ranges from 35 to 60% (sourced from the Canadian Centre for Occupational Health).

The CCOH article continues saying “The healthy human body maintains its internal temperature around 37°C. Variations, usually of less than 1°C, occur with the time of the day, level of physical activity or emotional state. A change of body temperature of more than 1°C occurs only during illness or when environmental conditions are more than the body’s ability to cope with extreme heat”.

As the work environment warms-up, the body tends to warm-up as well. The body’s internal “thermostat” maintains a constant inner body temperature by pumping more blood to the skin and by increasing sweat production. In this way, the body increases the rate of heat loss to balance the heat burden. In a very hot environment, the rate of “heat gain” is more than the rate of “heat loss” and the body temperature begins to rise. A rise in the body temperature results in heat illnesses.

Heat stress can occur in many workplaces including engine rooms, vehicles, shipping, bakeries, furnaces, foundries, glass production, outdoor construction, laundries, kitchens etc.

These hot environments reduce worker efficiency and:

  • Cause loss of concentration and the ability to do mental tasks
  • Loss of ability to do skilled physical tasks and heavy work
  • Increased irritability

Kool Wrap products can assist workers by insulating or deflecting heat away from the work area.

We have recently completed projects on diesel generators exhaust pipes and turbochargers and even exhaust pipes on fishing vessels.

Call Kool Wrap today and discuss your work place heat protection problems.

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Kool Wrap Can Prevent Harvester Fires

Kool Wrap prevents Harvester Fire

We had a customer call from Western Queensland and he wanted some wrap to go around a muffler that was causing fires on his harvester.

He said it was common for pieces of dry stalks, crop dust or chaff to gather on the harvester and this was particularly dangerous around exhaust pipes, mufflers and turbo chargers.

In fact, the GRDC (Grain Research and Development Corporation) claim that 7% of harvesters will start a fire EVERY YEAR.

The risk of fire varies depending on the weather conditions, wind direction and the type of crops with Chickpeas being one of the worst offenders.

This problem is not confined to the northern states. We have had reports of similar fire problems in southern states such as Victoria.

Wrapping of hot exhausts and mufflers is one way to reduce the risks.

Other methods include the frequent cleaning of the vehicle with high pressure blowers to reduce the build up of inflammable materials.