Re: Sharp Plasmacluster FP-P40cx/FP-N60cx Carbon Bag Swap

A Frequent Contributor writes:

Hello Ed,

Sorry to bother you again.

I've got another question about the Sharp FP-P40CX I recently purchased.

I've measured the filters in my unit against the filters in an old FP-N60CX on display in a local store (this unit appears to be very worn, otherwise I would have bought it!), and, despite the fact that the filters have different model numbers, the HEPA filter appears to be identical in size.

The carbon filter is the same length and width, but is roughly 3/8 inch thicker, and weighs significantly more (the carbon filter in the FP40 weighs about 10.5 ounces, the carbon filter in the N60 weighs somewhere over a pound).

I'd love to get more carbon into my 40CX, and was wondering if I could use replacement filters for the larger unit.

I think they could physically be made to fit; it might be necessary to tape the prefilter in place rather than fitting its tabs into the slots in the filter frame, but that should not be any big problem.

Any guess whether the heavier carbon filter would be likely to significantly impede air flow, and whether this might prove an issue for the motor on the FP40?

I hope you have (or had, depending upon when you read this) a wonderful Thanksgiving!

Best wishes,

Ed's Reply

Dude!

Absolutely no need to apologize - you keep coming up with great stuff.

Ironically, I also just bought a Sharp FP-P40CX and am preparing the initial review. Noticing the lightweight carbon bag, I thought exactly the same thing - will the bigger Plasmacluster's bag fit?

But as usual, it takes a reader email to prod this old dog into doing any work!

So, after your e-mail, I lined my two Sharps side by side and took them apart, stripping away the scotch tape I used to seal the FPN60's filter cassette tray.

The two trays are identical in width and height, but FP-N60cx's tray is about 1/2 inch deeper. The prefilter screens are identical, the HEPAs could even be swapped in a pinch.

This means that owners of the older 60-series sharps could use the newer 40 series parts as well.

My 60-series carbon filter bag has recently been refilled with all the fresh carbon it can hold, as compared to about 2/3 full from the factory.

It fits atop the HEPA in the 40's tray, but although the the prefilter screen snaps in, it buldges some, causing the outer cover to snap into place only under pressure.

But my bag is a fatso, the stock FPN60cx/FPP60cx bag should fit better.

Dressing the plastic tabs on the prefilter screen with a file, so they don't pressure the front cover, might also be possible.

In the photo below, on the left, a 2005 Sharp FPN60CX with 2009 FP-P40CX filter bag fitted. FP-P40CX is on the right with the bigger 60-series carbon filter bag installed.

You will probably need to tape the prefilter edges to keep macro dust from slipping around, but it looks like the swap can be made to work.

As you can see, there is lots of room for air to get around the bigger bag, especially mine with 3/8 inch trimmed off for refill.

Another possibility is to add carbon to the FP-P40cx bag. While it is smaller and has more chambers, the factory fills it just over 2/3 full.

Unlike the FPN60cx bag, the 40 bag has a blue seam, which I'd hesitate to remove. Maybe a series of 1/2 inch incisions on the back next to the seam, then add carbon and close as detailed in a previous post:

Plasmacluster Carbon Bag Refill

You'd need to use a smaller funnel and fill to maybe 90% full, but this should increase the stock 40's carbon by about 25%.

Your quality input is always appreciated, and I look forward to hearing any results.

Ed