Identify your sieve beds here ...
Substituting beds across different makes and models of concentrators
Sieve beds some in many sizes. Below we provide information on different models we have encountered. We have successfully replaced zeolite on all these models, most of which are designed for easy access for zeolite exchange.
DeVilbiss 515 beds, 450mm long (Part No. 515DZ-619)
These beds come with a flange on both ends. They are NOT designed to be refilled. However, it has been a common practice in the US for more than 20 years (with the older MC44 concentrators) to modify these beds for refilling. This is not a complicated process but it does require some investment in terms of making a tool to help remove the end cap and also in fabricating a replacement end cap. Below you can see the wooden jig we made to securely hold the sieve bed while we use an compressed air powered die grinder to cut into the flange. First make a deep non-penetrating groove all around the flange, then penetrate in one location. Use a strong pair of wire cutters to cut the flange in one location then use a pair of needle nosed pliers to peal the flange off. As the wooden support are positioned to match the exact length of the sieve bed the cap stays in place despite the force from the spring. Once the collar has been entirely removed you can carefully remove the sieve bed while holding in a vertical position so as not to loose any of the zeolite. Keep the spring, disk and fabric to be used when refilling.
Since the aluminum cap has been removed and cannot be replaced (please recycle the aluminum!), we install a custom-made PVC plug (see picture). The plug is made of 15mm thick blue PVC material with an O-ring installed to prevent leaking. The cap is secured with 3 equally-spaced 10mm self-tapping screw installed at 120 degrees. The O-ring is 70mm outside diameter and 3.5mm thick. The center of the plug is tapped with a 1/4" NPT thread to accept the brass fitting. PTFE thread taps is used when installing the brass fitting. Once the bed has been refilled and reassembled it is pressure tested to 40psi to ensure that there are no leaks. A vinyl end-cap is installed on both ends to prevent moisture from entering while in storage. Beds are labeled with the date on which it was refilled.
DeVilbiss 525 Beds, 300mm long ()
The DeVilbiss 525 concentrator uses as significantly smaller sieve bed with roughly half the volume of the 515. The 525 sieve beds can be found in refillable and non-refillable versions.
The refillable bed has a large cir-clip . This can be removed by first pressing down on the end cap to compress the internal spring then squeezing the cir-clip with a pair of pliers.
The plastic end cap version is not intended to be serviced. So far we have not developed a hack for this, but we will do so soon.