Sharp FPN40CX Air Purifier

Hydroxyl Radical Air Purifier Sharp Plasmacluster FPN40CX $279 to $399

Carbon and HEPA Air Filter FZ-N40HFU $90 to $107.00

  • Sharp Plasmacluster FP-N40CX has been superseded by the very similar FP-P40CX. The older version is disappearing from inventories. While the "40" is not reviewed yet, the new FP-P60CX model is reviewed here: Sharp Plasmacluster FP-P60CX Review

    Here is the ionic air purifying technology breakthrough. For those desiring an ionizer with near zero ozone that really gets after airborne contaminants, Sharp Plasmacluster is it.

    The FP-N40CX air purifier is the middle unit in the made for America product line. FP-N60CX, which I review, use and promote with enthusiasm, is the big brother. FP-N25CX is the baby bear, and the unobtrusive FP280WM is designed to mount on a wall.

    Good looking, extremely quiet, and possessing extensive electronic controls, this Japanese made ionizer-HEPA-carbon hybrid radical generating air purifier is rapidly establishing an international presence. I am very impressed with the cleaning power of these oxidizers, and purchased a FP-N60CX for testing in my home (see review, FP-N60CX).

fpn40cxThis radical-hydroxyl machine is a product of a world class corporate giant, with units customized, and marketing tailored for, each regional market. See my Sharper Image Ionic Breeze review for my theory of how ozone based oxidation plays a subtle, but central role in the ionic air purifier success story.

    Many builders are racing to gain some of the "breeze" market share in the booming air purifier market. Sharp had a pretty decent research and development budget on their hydroxyl air cleaner project, and it shows. A vote of confidence comes from Sears, which has licensed this hydroxyl air purifying technology for marketing as the Kenmore Envirosense air purifier.

    The FP-N40CX and its brothers combine passive air filtration, traditional HEPA and carbon, with active hydroxyl radical based oxidation to permanently remove air contaminants. Electrically charged molecules (ions) diffuse out into the air and attach to any surface or particle. These ions create "free radicals" which oxidize and destroy airborne allergens outside the radical-hydroxyl purifier.

    Notice that this air purifying happens at the molecular level, irrespective of particle size. Tiny sub-micron particles and complex toxic organic molecules are removed from the air. Bacteria, viruses, mold, pollen, cat or dog dander, and other allergens are destroyed. (No air purifier can remove carbon monoxide from indoor combustion and smoking) Large particles like pet fur and human hair must be filtered, but the tiny (>.1 micron) lung penetrating particles, which elude other air purifier technologies, are removed.

    Hydroxyl cluster ions last from 3 to 5 seconds, allowing them to move and act at a distance from the air purifier. Based on an estimated exhaust air velocity of 2 feet per second, radical-based air purification could extend as far as 10 feet from the air purifier. This would be perfectly adequate for the FP-N40CX prescribed room size (253 sq. ft.). There is no need to debate vendor claims of extremely fast and distant diffusion, which I have seen on the web.

    Laboratory tests have shown the airborne hydroxyl radical to be effective at reducing the airborne viruses that cause influenza and the common cold.

    I was skeptical about the ability of this air purifier technology to operate at a distance, but after buying and using the Sharp purifier, I am a believer. This air cleaner technology doesn't just capture air pollutants, it rips 'em out by the roots. In my opinion, air radicals are so powerful that, like "safe" levels of ozone, hydroxyls represent a risk to the uninformed.

    The hydroxyl radical is among the strongest oxidizers known; stronger than ozone, stronger than chlorine (bleach, connected to breast cancer). I have had reactions to my air purifier when operated in "clean" (hydroxyl radical generation) mode. It burns the tissues of my nose and stings my eyes after an hour or so. It feels like little mosquito bites on exposed skin. I believe the following will be the long term results of air purifiers with this technology.

    1. Incredible active cleaning power.

    I recently moved to an apartment which is toxic with fresh paint, new carpet, old air ducts, and kitchen countertop sealer. I have a top quality HEPA air purifier (IQAir) in my bedroom. This is passive filtration, it must wait for the chemicals to volatize and become airborne. I believe the plasmacluster oxidizer technology, like ozone, can attack and destroy odors and toxic chemicals which are still in source: paint on the wall.

    Improvements in sleep quality, and eye/nose irritation have been noticed, above what had been achieved with my collection of air purifiers (got 7 in a 700 sq. ft. apt). I move my FPN60CX around the house to detoxify the paint and countertops, but I don't stay in the room when my hydroxyl air purifier "Superman" (blue light) is making radicals. A simple click with the remote changes it back to (green light) "Clark Kent", a true HEPA with good carbon and ozone-free traditional negative ionizer. So cool.

    2. Dangerous free radicals are released!

    Hydroxyl radicals are real bleaching power and is not safe to sit or sleep near the air purifier. The radical purifier destroys microrganisms in the air by cutting holes in their cell walls: our bodies are also made of cells. I use the blue light plasmacluster ion function in the vacant bedroom days, and the green negative ion function at night. Used properly, FPN40CX is a safer alternative to ionizers and ozone machines because the ion clusters and resultant airborne hydroxyl radicals produced have very short lives, decaying away seconds after the blue light is out. It is convenient to use the remote to change from blue (plasmacluster) to green (plain negative ionizer), wait a few seconds, then approach the air cleaner.

    I recommend using the "blue light" Plasmacluster cleaning function in empty rooms only.

    Purifier with Hydroxyl Radical: Quiet Power!

    With Association of Home Appliance Manufacturers (AHAM) certified Clean Air Delivery Rates (CADR) of dust 157, smoke 163, and pollen 156, FPN40CX moves enough air to actually clean a 253 square foot room at 6 air changes/hr.

    The Sharp FPN40CX operating in quiet mode puts out a claimed 15 dB(A)@18cfm. This is industry leading quiet. On high speed, with clean air delivery rate averaging an acceptable 159, a claimed 44 dB(A)@141 cfm is also a pretty good air volume to noise ratio. 38dB(A)@60cfm in second gear is very good performance for bedside use.

    These are the lowest sound levels I have found for a unit that actually cleans meaningful volumes of air. This thing is so quiet, running five feet from my bed, I must turn my head to look at the light to see if it's on.

    No Ozone?

    Other ionizer air purifiers produce ozone as a by-product. Ozone cleans by oxidation, but persists in living spaces, decaying in time measured in days, not minutes as is widely asserted by proponents. Plasmacluster FPN40CX produces less than 10 ppb (>.01 ppm), the lowest of any ionizer. When the hydroxyl creating "clean" mode is off, it's a powerful, safe conventional negative air ionizer.

    The manufacturer asserts that the Plasmacluster does not out-gas, and is safe for use with multiple chemical sensitivity. This statement is not completely true, as detailed above. I consider this air purifier perfect for MCS, when used as specified above: use hydroxyl radical generating in unoccupied rooms only.

    What? Hydroxyls, HEPA air filter and Carbon, too?

    In normal household use both True HEPA and Granular Carbon air filters do not require replacement for three to five years. A washable prefilter, framed to last indefinitely, like those on air conditioners, removes large dust and dirt particles from the air. No prefilters to buy start the pattern: very low long term air purifier cost of ownership.

    Over a pound of granular activated carbon is enclosed in a pleated polypropylene and polyester bag to make a washable odor filter with much higher capacity than typical carbon impregnated cloth filters. FP-N40CX is claimed to remove over 4000 VOC chemicals.

    When the carbon filter is washed every two months, it is projected to last five years. Washing is some work; vacuuming, soaking in mild detergent, brushing, and hanging for complete drying.

    The FPN40CX true-HEPA air filter is polypropylene in a polyester frame to reduce out gassing and microbial growth. I consider the framing a bit weak, and would prefer a rigid frame and tighter gasketing.

    HEPA is placed second, ahead of the ion generator, to capture particles that may be released into air flow by components upstream. HEPA spec is satisfied: the filter traps over 99.97 % of particles down to 0.3 micron.

    Very long filter replacement intervals add to the picture: overall low cost of ownership.

    Good looking and Smart.

    Automated air purifier technology is the future, and this unit is at the frontier. The oxidizing feature is controlled through the remote. Clean Mode is functioning when the indicator light is blue, signaling that both positive and negative ions are being emitted into the air. Ion Control Mode, when the light is green, emits only negative ions, cleaning by flocculating (clumping) particles, like traditional ionizers.

    Auto Mode switches the hydroxyl generating function off and on, and controls fan speed, using an odor sensor. FP-N40CX does not have a particle sensor like the 33% more powerful FP-N60CX. With so many air purifiers in my apartment, my air is very clean. I do use "auto" mode, but it turns on the oxidizer functions infrequently, every aspect is easily user controlled.

    Pollen mode cycles the unit on a timed schedule. Manual Mode allows complete user control.

    An elaborate LED displays the current operating mode, current air quality, and filter cleaning reminder. I was initially attracted to these air cleaners by the sensor features. My Sharp can tell when the bedroom window, open a tiny crack, has let in a whiff of that good uptown Houston outdoor air. Users report the Sharp FPN40CX air purifier can "smell" whether the gas log is lit, who is wearing cologne, if something is on the stove, and if nobody took out the trash. They also complain about the lack of dust sensor on FP-N40CX. FP-N60CX has both air sensors.

    The comprehensive remote control is large, but fits well in my hand. Some users complain about having to single-step through each fan setting. Use the remote to turn off the lights and change speeds at night. The timer can be set for 1, 4 or 8 hours delayed shut down. I find the remote convenient and easy to use in the dark.

    Some other models, notably the Ionic Pro, Ionic Breeze, and Blueair, generate gripes about bright lights at night. Using the remote, Sharp Plasmacluster's lights can be turned off at night, leaving just the small green fan speed light and the air quality indicator on. Please note that turning off the lights conceals whether the air purifier is producing the oxidizers: be sure to go to green mode first.

    Beyond Energy Miser

    Using only 3 watts of power on low speed and 25 watts on high, the quiet DC motor is cheaper to run than some nightlights. Air-Purifier-Power never rates noise or energy use alone: it must relate to work done. A junk car in the back yard uses no fuel, but won't get you far.

    As with noise, the results are astounding: 28 cfm air volume at just three watts on "silent" speed. FPN40CX blows a meaningful 88 cfm in second using only nine watts of power. Sharp's ionic oxidation machine is the absolute champion of the EPA energy star ratings, scoring an unbelievable best by a large margin 6.3 (dust CADR per watt). Typical energy star scores are 3 to 4. Starting to look like the lowest overall cost of ownership, relative to actual air cleaning acomplished, of anything on the market.

    With dimensions of 16 3/8" x 22 1/2" x 7 15/16", weighing only 15.4 lbs, with a well balanced handle, Sharp Plasmacluster FP-N40CX is actually portable. Using 8.3 feet of cord, the FPN40CX won't need to hover in front of an outlet.

    Hydroxyl Purifier Flaws

    Every air purifier design project involves tradeoffs. FPN40CX, with incredible quiet power, long filter life and low energy use, has a few.

    This unit inhales through the front and exhausts at the top, concentrating the typical ionizer's “black wall effect.” The wall behind the air outlet, curtains, or furniture may become soiled. I move mine about three times a day, to stay close to the negative ions, not to save the walls.

    Enough space should be left between the purifier and obstructions for air flow to cool the motor.

    Some consumers note weakness, but not fragility, of the front cover retaining clips.

    I wonder if the method of securing the fragile HEPA filters in retainer trays may allow light bypassing and compromise small particle efficiency. Of course, FPN40CX is primarily an ionizer, not a big high-static-pressure HEPA air cleaner.

    The low voltage DC is applied only to the fan motor, which probably reduces its electromagnetic fields (EMF), but what about the ionizer's EMF? Of course, every air purifier has EMF issues. I am very sensitive to electricity, but I can run the low watt hydroxyl generator at very close range. I notice the expansion and collapse of the ion wire field, accompanied by a light pinging noise, when lying very close to my air purifier.

    An air purifier with electronics has lots of bells and whistles to fail, and air odor and particle sensors must be kept clean. The user's manual contains cleaning instructions and a lengthy troubleshooting guide.

    Some consumer reviews and the product manual refer to a slight ticking sound heard when the unit is generating ions. You must be very close to hear it. While the hydroxyl radical producing air purifier is generating negative ions this ticking is minor.

    Sharp's hydroxyl radical machine is marketed primarily through electronics vendors and vacuum cleaner outlets, rather than allergy or air purifier retail specialists. This marketing channel, where the company had previously established connections, is sometimes less flexible on returns and warranty service. Some sites refer all problems to the manufacturer.

    The limited warranty covers parts and labor for only one year. Sharp has a system of contract agents who come to your location to service warranty claims.

    Manufacturer Has Staying Power

    Sharp Plasmacluster FPN40CX hydroxyl generating air purifier is made in Japan by a global leader in microelectronics. Sharp products include Liquid Crystal Displays (LCD), HDTV, 3g mobile phones, thin-film photovoltaic power systems, and a wide range of consumer and industrial electronics.

    Introduced in 2003, Sharp's hydroxyl radical machine quickly became the top selling air purifier in Japan. Sales in South Korea, China, Canada, Australia and UK are substantial.

    It is important to realize that the air cleaner market is fragmented globally, with completely different models in other parts of the world.

    Even Canada and Britain have distinct regional market identities. When this boom matures, a global air purification shakeout is inevitable: think of all the brands of personal computers that vanished recently.

    The company has significant US penetration and sales growth, with customer service handled out of Romeoville, Illinois. Stateside customer service has presented problems for Japanese vendors, and Sharp is no exception. But when many air purifier builders working today are gone, I think Sharp will still be a player.

    Note that these air purifiers, marketed outside the "price inflexible" US allergy store distribution chain, is sold for widely varying prices. FP-N40CX has a varying price history; introduced into strong demand in 2003 in the $300s, prices peaked around $400 in the summer of 2004. As the number of sellers increased, prices fell to a low around $280. As always, seller reputation is as important as price for internet deals.

    New model introductions should drop price on these units, but the public is seldom aware of this. Dealers will move obsolete inventory "brand new in original box." Sharp Canada is selling a new version with "r" in the model number: FPR45CX. It has double the ionizing power. Sharp's next move is anybody's guess.

    I absolutely adore Sharp's air purifiers, I use and endorse them with the warning: use the Plasmacluster oxidizer "clean" and "auto" blue light functions while people and pets are out of the room until your space is clean enough for auto mode to run mostly on green light.

    Air-Purifier-Power Rating

    Sharp Plasmacluster FPN40CX: 88, very good ionizer.

    Each of ten factors gets up to 10 points, 100 is perfect and very unlikely.

    1. First do no harm; minimal out gassing, no ozone.

    Score: 7 of 10, every builder says their ozone levels are "safe", Sharp has set the standard for ionizers. I think ionic radical/hydroxyl oxidizing power is dangerous to the uninformed, and safe when used properly.

    2. Serious gas and odor removal is a requirement if health benefits are expected: Air purification units with real carbon VOC capability rank higher.

    Score: 10 of 10, washable one pound carbon air filter combined with ion-oxidation system actively gets after chemicals.

    3. Quality construction; case, gaskets, seals, and precision fitting eliminate air bypassing and assure high efficiency at filtering sub-micron particles.

    Score: 8 of 10, ar filter basket system suggests mild leakage, but HEPA is not the core technology.

    4. The design maximizes the lifespan of each filter stage by allowing independent filter replacement. Ideally this is combined with electronic air filter monitoring.

    Score: 10 of 10

    5. Unit has long air filter life, low maintenance requirements, and reasonable operating costs.

    Score: 10 of 10, Hydroxyl radical technology air purifiers are cheaper to own than lower priced units.

    6. Purifier produces low noise levels and meaningful air flow rates relative to noise.

    Score: 10 of 10, world champion of quiet cleaning. US builders had better notice what happened to autos, microwaves, and personal computers.

    7. Manufacturer has a track record, with many air cleaners in the field and a reputation for supporting what they sell. Warranty period and average service life are long.

    Score: 7 of 10, warranty is shorter than filter life.

    8. Air purifier is a value in terms of price/performance ratio. Every price range should be included, “models above $1,200 are best”, while true, is not useful to most consumers.

    Score: 8 of 10, good functionality at a middle price, I prefer the larger Sharp FP-N60CX: 33% more power, 16% higher price.

    9. No dirt; unit and manufacturer should be devoid of class-action suits, high returns, recalls, consumer complaints, and legitimate negative consumer reviews.

    Score: 8 of 10, some consumers of Sharp television sets have complained of poor customer service.

    10. Unit is stylish, portable, comfortable, and convenient for consumer use.

    Score: 10 of 10, handy remote, easy interface.

    Numeric Rating; 88

    very good ionizer, danger and opportunity, hydroxyl oxidation radical technology safe for informed users in empty rooms only.

    Sharp Plasmacluster FPN40CX Air Purifier: Breakthrough Hydroxyl Radical Technology.

    Through July 31, 2006, Sharp has a $100 mail in rebate on FPN60CX and FPN40CX, just print out the .pdf file at Amazon: Rebate Coupon at

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