Tips to consider when installing BLDS in Baghouse Dust Collectors
We have seen a wide range of installations over the 40 years we have been in the triboelectric electrostatic bag leak detection system field… Most of them successful and also a few that may have left a bit to be desired – from welding the mounting ferrule upside down - or not wiring the outputs and wondering why there was no alarm. Rest assured that installing a BLDS in a Baghouse Dust Collector is not overwhelming, and by using the documentation with the appropriate guidance the process should be relatively painless.
Optimally, the best installations occur when an end user or contractor communicate with the manufacturer prior to production and shipment of the product (review application details, drawings, etc). This can ensure appropriate guidance is offered specific to the installation details. When this occurs, installation issues seldom occur.
But appreciating that our customers, re-sellers, partners, and Baghouse or Dust Collector OEM’s don’t always have the time to discuss details of installation in advance, we thought it may be helpful to send out a few simple tips – or things to look out for specific to installation:
Tip #1 - Where should I install the bag leak detector probe?
The best location for the probe is in a straight section of pipe or duct. If possible, having at least 1 diameter upstream and down stream of the probe. The longer the straight section the better. Avoid elbows, dampers or any other interfering equipment. It is also a good practice to avoid installing the probe in the final vertical stack which may allow the probe to be exposed to the weather (rain, snow, etc.). This can result in requiring more probe maintenance over time due to frequent build-up on the probe.
Tip #2 - Improper signal cable preparation
Triboelectric bag leak detectors and dust monitors are sensing very small electrical signals measured in pico amps. Because of this, special proprietary low noise coaxial cable is used to connect remote probes to the monitoring electronics. This is not standard coaxial cable, so it is common that electricians and installers often think they know how to prepare the cable ends when in fact there is a special black semi-conductive layer that must be properly scraped back to insure a good connection. When a cable is made improperly it can result in either a very large offset signal or the opposite – a very low non-responsive signal. Make sure that whoever will be handling the installation is informed and follows the correct preparation directions per the supplied drawing and instructions.
Tip #3 - Mounting the probe properly in the pipe or ductAnother common problem we see in the field is the improper installation of the probe onto the pipe or duct. The sensing probe is made up of the exposed probe and insulator which isolates the probe from the duct wall. Proper installation is too make sure that the insulator and probe are placed so they are completely in the stream. Often we find that the standard mounting hardware has been welded onto an existing stand-off or nipple which then sets the probe back into this space. The result is false signals due to bridging of material build-up within the stand-off or nipple.
The best way to avoid this occurrence is to review drawings and have a conversation with the engineering team or installers. When we find that the installation has already been done we can also re-work the probe to fit the new mounting scheme or in some cases we have even provided an insulative sheath that can be installed in the field to cover the recessed portion of the probe provided the remaining probe will still reach to at least 50% of the duct diameter.
Tip #4 - Proper installation of conduit to connecting glands/hubs
Another common installation problem is finding water inside the electronics enclosure or the head for the remote probe. This is usually caused by improper sealing of conduit to the enclosures. Best practice is to use a loop of flexible conduit that dips below the level of the enclosure and add a drainage hole at the bottom of the loop. (often called a drip loop)
Tip #5 - Can coaxial cable be run with other wiring?
Many installations try to optimize the conduit they run by putting multiple cable in a single run of conduit, or they may use cable trays. Because of the special nature of the signal cable and the very tiny signals it conveys, coaxial cable SHOULD NOT be run along with any power wiring. Best practice is to use a dedicated run of conduit. However, it may share conduit with 4-20 mA wiring or other low-voltage signal wiring.
Tip #6 - Mounting hardware installation issues
Welding overrun (also called welding slag) can encroach upon the opening of the half-coupling (for NPT installs) or the ferrule (for quick-release installs). This can cause damage to the probe or insulator when pulling for service.
For proper installation the half-coupling or the ferrule should slightly protrude into the installation hole. It is important to review the installation drawings for proper hole size to prevent welding issues or mis-alignment of the holes.
If there are additional issues that you may have seen or heard about in the field specific to BLDS and Baghouse Dust Collectors, let us know! We are always interested in helping to convey experiences we have seen and worked on with our customers, but we also love to learn – and its important as we continue to try and offer best suggestions and guidance.
Also, please take a look at our Guide to 15 Tips for Selecting the Best Bag Leak Detection: