Duct Balloon

 Inflatable Isolation Barriers

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How is it installed in the duct work?

Bring the Duct Balloon and blower to a location near the access door. Remove it from the storage bag. Carefully feed the balloon through the access door opening to the work area where you want to install it. Run the inflation tube back out the access door to the blower. The balloon has anchor rings sewn into the top corners for lifting it in place if required. Most balloons less than 20’ (6.09m) high can be maneuvered in place during the inflation process without hoisting. Connect the inflation tube to the blower and then turn the blower on. As the balloon starts to inflate, it can be maneuvered into position by using the supplied grab handles. To see a short video clip of a 19’ (5.7m) high x 10’ (3m) wide x 3’ (.9m) deep Duct Balloon being inflated and deflated, click here.


How accurate must my dimensions be? The Duct Balloon is designed using the existing duct work dimensions that you provide. It is designed to inflate larger than the dimensions you provide in order for it to create a tight seal. While actual field dimensions are preferred, dimensional information can be taken from plant drawings, or taken outside the duct work when the unit is operating. Be sure to take into consideration the thickness of any existing insulation that maybe present on the outside the duct work.


How is it deflated when you are done? Turn off the blower. Remove the inflation tube from the blower discharge by opening the Velcro attachment and safety strap. Then pull open the deflation zipper on the balloon and it will quickly deflate.


To what temperature is the material rated?

Each material we offer has different temperature/time limits and is selected based on the information provided by the end user.  We have materials rated up to 500ºF (260ºC). The amount of time that the Duct Balloon will be exposed to high temperatures greatly affects its service life.


Where does the blower need to be located?

The blower can be located a few feet from the balloon, or it can be 100' (30.4m) or more away from it. It is preferred to locate it in a clean area on grating outside the duct work away from any fly ash that maybe present. Care should be taken to keep the blower intake clear of any foreign matter or objects. The blower can be left outside the duct on grating as it weather resistant but not waterproof.


Can I inflate the balloon once and then remove the blower?

No, the blower system must remain on at all times to keep the balloon fully inflated.


What voltage blowers do you offer?

We can supply the blowers in 110V-50Hz, 120V-60Hz, or 240V-50Hz


If the blower must always remain on, is it very expensive to run?

Electric rates vary by location, but overall the cost is minimal. The motor that powers the blower draws between 6 to 11 amps.


If the blower loses power, will the balloon start to deflate?

There is a back flow device on the blower discharge which will keep it from deflating immediately, but the balloon will soften and eventually deflate. In areas where this could cause concern, we can supply a two blower setup for redundancy. Due to its design, a Duct Balloon cannot become over pressurized by using two blowers simultaneously. If loss of power occurs to the one of the blowers, the balloon will remain fully inflated by the backup blower as long as each blower is connected to independent circuit breakers.This has been done in the past on SCR or FGD applications .


Can I use my own inflation tube, and what size is it?

No, the inflation tube can be made from the same material as the Duct Balloon. It inflates to 8” (203mm) in diameter. We normally furnish 25’ (7.62m) of inflation tube for use between the blower and the balloon, but any length can be  provided. If there are numerous 90º turns between the blower and the balloon, we can supply spiral wound Flex-Duct inflation tube. Care should be taken to determine the correct length of either type of inflation tube. Too long of an inflation tube can become a tripping hazard.  


How much does one of these balloons weigh? A 12’ (3.65m) x 12’ (3.65m) x 3’ (.9m) size Duct Balloon weighs about 32 lbs. ( 14.5kg.)  An 18’ (5.48m) diameter x 5’ (1.5m) thick disc shaped balloon weighs about 50 lbs. (22.6 kg.) The blower weighs about 43 lbs. (19.5 kg.) We furnish estimated weights for the Duct Balloons in our quotations. To see a weight chart of various sizes, click here


Can I use station air to inflate the balloon?

No, each balloon must use its own 120V or 240V positive pressure blower.


What if the balloon gets torn, will it deflate?

Small tears will not cause the balloon to deflate as long as the blower remains on. We can furnish a repair kit that includes 5 square feet (.46 sq. meter) of material and adhesive for small on site repairs. Or it can be sent back to the factory for a more permanent repair.


Can I use a larger size balloon for an opening that is slightly smaller?

Yes, it maybe OK to use a slightly larger balloon in a smaller size existing duct work, but you should check with us first. We maybe able to use a Multi-Section design so it can be used in more than duct size.


How does it compare in cost to other types of temporary barriers installed by our plant  personnel or contractors?

Labor rates vary by location, but many customers have told us that the Duct Balloons usually pay for themselves in the first installation and removal, because they are reusable.


What if I have structural supports in the area I want to install the balloon?

You may have to look at installing it in a different location. Most expansion joints are about 2’6” (762mm) wide, and a 3’0” (914mm) deep balloon will fit nicely in this area and provide a tight seal. Click here for more information.


How large or small can these balloons be made?

While there are no size limitations, the weight of the balloon can become prohibitive, as well as the access door it must go through. Duct Balloons for very large duct works can be supplied in sections that mate together to make them easier to install and remove. Small duct balloons can be made for pipe sizes from 48” (1219mm) in diameter and larger.


How much differential pressure will it take before it begins to move?

Amounts can vary greatly based on the duct work size and shape, frictional characteristics of the balloon material, method of restraint, the condition of the duct walls, etc. If you can provide the operating pressure of the duct work where the balloon will be installed, we can provide you with predicative holding values using calculations based on actual testing by a major university.


We may be grinding or welding near the balloon, so how can  we protect it?

The balloon can be supplied with additional anchor rings sewn into it at 24” (609mm) centers so that a fire retardant blanket can be clipped to it to prevent damage.


Do you need to erect a support structure to keep it in place?

Normally the balloon will hold tightly against the wall of the duct if sized and installed properly and the operating environment is only a natural draft. If the balloon can be installed near existing structural steel in the duct as shown here, then movement can be prevented. If there is no support steel present, then pad eyes can be installed in the duct work before the installation of the balloon.  Nylon rope or straps can be attached between the tie down point and the anchor rings on the balloon can help to minimize movement. Supports or tie downs should be always be designed by a professional engineer who is experienced with structural design. Many variables can affect how well any type of temporary barrier will seal properly including Duct Balloons. These are Duct Balloon size, depth, surface conditions, method of restraining, pressure, temperature and the integrity of the installation.


Does it come in a storage box so I can safely store it until my next outage?

The balloon, blower and inflation tube is shipped in a heavy duty vinyl storage bag with a draw string top. Fiberglass knock-down type storage boxes are available for an additional cost.


Can the balloon be exposed to sunlight or high humidity conditions?

The material that the balloon is manufactured from is UV resistant and is also impregnated with a mildewcide to inhibit mold growth, so sun or high humidity conditions will not affect it.

Copyright © 2017 by  G.R. Werth & Associates, Inc. - All rights reserved - Duct Balloon is a trademark by  G.R. Werth & Associates, Inc.