Compared with the water purifier under the kitchen, I think that the pre-filter is now a must-have water purification product for every household. But looking at the Internet, I found that there are still relatively few in-depth reviews about pre-filters.
As a researcher of home appliances, the "no-man's land" in the field of home appliances naturally has the courage to explore.
So this time, I paid 5,000 yuan + to buy five high-end pre-filter products on the market to see if their actual filtration effect can really ensure the health of domestic water.
I will start with five parts in this assessment:
- Exterior structure
- Parameter comparison
- Retention rate testing
- Flush rate test
- Disassembly analysis
I believe that after reading this comprehensive test article, everyone will also have a clear understanding of the filtration effect of the pre-filter.
First, the appearance structure
1. Structural design
Among the five pre-filters, Midea, Smith and 3M do not use a display design; The BKA is equipped with a water pressure monitoring meter for water pressure monitoring; Honeywell features a display, powered by three AA batteries, touch-operated display that can set the timing of automatic processing.
For the flushing reminder, Midea also has a user-friendly design - equipped with a time dial. The function is to set a time reminder so that we can rinse the filter regularly.
In terms of installation method, Honeywell, Smith and 3M all use the vertical installation method.
This installation method is relatively single, for users such as limited space under the kitchen and narrow equipment room, a single vertical installation method may not be able to be installed.
The BKA and Midea pre-filters support multi-angle installation, and the angle can be adjusted according to different installation spaces.
In order to see the actual installation effect of the two in the under-kitchen space, I specially disassembled the water pipes in the under-kitchen space and installed two pre-filters in turn.
According to actual measurements, if the under-kitchen space is relatively large, BKA and Midea can be installed horizontally and vertically, and the angle can be adjusted according to the actual size of the under-kitchen space.
However, the spatial adaptability of the BKA pre-filter will not be as beautiful as the beauty, because the volume of the BKA pre-filter is large, and the angle can not be adjusted when facing a narrower kitchen space or equipment well. In contrast, the 125m small volume Midea pre-filter can be applied to more diverse kitchen spaces to meet the installation needs of small spaces.
2. Material analysis
If the practicality of installation largely depends on the structural design, then the key to drinking water experience depends on the material of the pre-filter.
The material of the pre-filter can be divided into three main parts: filter bottle, copper head pipe fittings and filter screen.
The quality of the material used, in addition to being directly related to the service life, will also affect our drinking water health.
In order to let you more intuitively understand the different materials of the five pre-filters, I summarized the following table:
Through the above table, it can be intuitively seen that the filter bottle solutions used in the five pre-filtration are different, but we mainly focus on its explosion-proof, anti-freeze and safety performance.
Among them, Midea, BKA and Honeywell have the best performance, all of which have undergone 200,000 water hammer tests, extreme cold temperature difference tests of -30°C, and the materials used do not contain BPA.
As an international big brand, Smith and 3M have some "shrinkage" in the material used in the filter bottle. The filter flasks have only undergone 150,000 water hammer tests and do not label themselves as having been tested for extreme cold at -30°C.
It should be noted that bisphenol A is used to synthesize materials such as polycarbonate (PC) and epoxy resin, but bisphenol A can cause endocrine disorders and threaten the health of fetuses and children, so it is generally recommended to contain bisphenol A on children's products.
In terms of the material of copper head pipe fittings, it can be roughly divided into three categories: ordinary brass, low-lead/lead-free copper and lead-coated copper mouth.
Among them, the lead-coated copper mouth has the highest process requirements for manufacturers, but the copper head will not contact with water throughout the process, and it is also the safest material.
According to the classification, among the five pre-filters, Honeywell's copper head material is the best. Honeywell uses a physical lead insulation scheme, the internal POM layer, the outer copper layer specific what material is not officially stated, in theory this material structure is very safe, but the lead barrier coating on the manufacturer's process requirements are extremely high, the specific copper head durability performance, but also time to verify.
However, all manufacturers are advertising their own lead-free copper or lead-coated copper mouth, but whether the copper head pipe fittings contain lead is not hand-held, this time we will Honeywell and Midea, BKA copper head pipe fittings entrusted Shenzhen Tengbiao testing laboratory for testing.
In strict accordance with the national standard GB/T5121.3-2008 for the determination of lead content, the Zeeman effect electrothermal atomic absorption spectrometry method is used for determination.
Copper materials must meet the following two conditions at the same time to be considered as lead-free copper pipe fittings:
- Mass fraction of copper≥ 99.99%
- Mass fraction of lead< 0.00005%
It took 20 days for the lab to finally deliver the results, which can be calculated according to the following formula:
- Honeywell Copper Mass Fraction < 99.99%, Lead Mass Fraction > 0.00008%
- Midea has a copper mass fraction ≥ 99.99%, lead mass fraction < 0.00005%
- BKA copper mass fraction≥ 99.99%, lead mass fraction < 0.00005%
From the above lead content determination, it is not difficult to find that the physical lead barrier scheme used by Honeywell is somewhat "moisture", while Midea and BKA's lead-free copper materials have withstood the test of testing.
In contrast, Midea and BKA copper head materials will be preferred, because the lead-free copper head used in both is guaranteed in terms of safety and durability.
Smith and 3M are still bottom performers. Among them, the copper head used by 3M is an ordinary copper head, and Smith also has a bacteriostatic function.
The final filter material needless to say, the filter screen of the pre-filter is mainly made of 316L stainless steel, which has the characteristics of high temperature resistance and corrosion resistance. Among the five pre-filters, only 3M uses ordinary stainless steel, and its high temperature resistance and corrosion resistance will be relatively weak.
Second, parameter comparison
For the parameter party, the most important thing to start the pre-filter is to look at the product parameters, so the parameter comparison can not be less.
By asking customer service, consulting information, and consulting relevant R&D teachers in the industry, I summarized the various parameters of the five pre-filters and drew the following charts:
The top three frigates in terms of flux and outlet speed of the five pre-filters are Honeywell, BKA and Midea frigates, with fluxes of more than 6T/H and 100L/min.
In contrast, the 2.5T/H flux of Smith and 3M is somewhat stretched.
The filtration accuracy is one of the factors affecting the filtration effect, and the most suitable filtration accuracy recognized by the industry is 40μm, which can not only reduce the blockage of the filter screen, but also filter out most impurities.
Among the five pre-filters, Midea, BKA, Honeywell and 3M all have a filtration accuracy of 40 μm, and only Smith has a filtration accuracy of 100 μm.
Since the pre-filter plays a filtering role, it will inevitably produce impurities that are filtered, and how to dispose of these impurities is the key problem of the pre-filter.
The key to the effect of treating and filtering impurities depends on the rinsing method of the filter.
As far as the flushing methods of pre-filtration on the market are concerned, they can be mainly divided into direct flushing type, recoil type and siphon type, of which the flushing effect of the backflushing type is the best.
After comparison, the five pre-filters of Sino-American, BKA, and Honeywell all adopt the backflush type, and also support the scraping function.
BKA and Honeywell can also achieve double-sided scraping. The flushing method of Smith and 3M is a direct flush type, don't look at the 3M's flushing method named vortex type, its essence is still the same as the direct flush type.
Finally, briefly talking about the features of the five pre-filters, I personally think that Midea's frigate and Honeywell will perform better.
In actual domestic water, if the pipeline is not specially treated, it is prone to water hammer effect. The water hammer effect is highly destructive and can easily cause pipeline rupture and valve damage.
In order to avoid the negative effects of the water hammer effect, Midea's frigate gave a different solution.
It is equipped with a water hammer eliminator, that is, the continuous reaction of the water hammer effect is eliminated through the water hammer elimination valve, which not only reduces the irregular water shock wave oscillation in the water pipe, but also solves the problem that the water hammer effect may cause the water pipe to rupture.
BKA is equipped with a water pressure monitor, which is convenient for us to understand the current water pressure intensity, but the role is not too obvious from the actual experience;
Honeywell is more convenient for our daily use, it supports intelligent filter self-cleaning, can customize the rinse time, and performs automatic scraping, reducing the number of human operations.
In contrast, Smith and 3M do not have more distinctive functions and belong to decent pre-filter products.
Third, the retention rate test
· Test purpose: To verify the filtration effect of the pre-filter with a filtration accuracy of 40μm and above the impurities of 40μm size
· Experimental equipment: purified water, silica powder, thousandth balance, Brinell funnel, drying blower, self-built waterway simulation equipment
· Retention rate calculation formula: [(M-m1)/M]*100% = Retention rate
No matter how many paper parameters are said, it is better to measure them as the most practical.
Since the pre-filter plays a filtering role, it is naturally most important to test its retention rate.
Since the test is a pre-filter with a filtration accuracy of 40 μm, and the filtration accuracy of the Smith pre-filter is 100 μm, it can basically be concluded that its retention rate is the worst before the test.
THE EQUIPMENT IS PREPARED BEFORE THE TEST, AND 2.000 GRAMS OF SILICA POWDER IS WEIGHED AND MELTED IN 1000 ML WATER.
Follow this procedure to prepare aqueous silica solutions for each of the five pre-filters. To ensure consistent concentrations of impurities in each serving of water and avoid test inaccuracies.
Each pre-filter is installed in turn on our self-built waterway simulation equipment, as shown in the figure:
Put the prepared water containing impurities at the water inlet, turn on the water pump, and use the measuring cup to catch the filtered water at the water outlet.
The qualitative filter paper is then laid in the Brinell funnel, and since the pore size of the shaping filter paper is only 15 μm, the silica impurities in the water can be filtered onto the shaping filter paper.
After a period of filtration, it can be seen that part of the silica powder adheres to the surface of the qualitative filter paper.
Then the qualitative filter paper is put into a blower for drying, and after a certain period of time, a little silica powder is attached to the dried qualitative filter paper. Separate measurements yield:
· The silica powder obtained by Honeywell after filtration and drying weighs 0.177 grams;
· The weight of silica powder obtained after BKA filtration and drying was 0.198 grams;
· The weight of silica powder obtained after filtration and drying of Midea is 0.180 grams;
· The weight of silica powder obtained after filtration and drying by 3M was 0.214 grams;
· The weight of silica powder obtained by Smith after filtration and drying was 1.844 grams;
The total mass of 2.00 grams of silica is set to M, the mass of silica powder obtained after filtration is set to m1, and combined with the formula [(M-m1)/M]*100% = retention rate, the retention rate of each filter is calculated as follows:
· Honeywell: 91.15%
· BKA：90.1%
· Midea: 91%
· 3M：89.3%
· Smith: 7.8%
The retention rate of the four pre-filters is quite good, with Honeywell having the highest retention rate - 91.15%, followed by Midea's 91% retention rate.
In addition, since the filtration accuracy of the Smith pre-filter is 100μm, after excluding the experimental error, the actual interception rate of the Smith pre-filter can be basically regarded as 0.
4. Flushing rate test
· Purpose of the test: To verify whether the trapped impurities can be flushed when the pre-filter is rinsed with the filter
· Experimental equipment: pure water, thousandth balance, Brinell funnel, drying blower, self-built waterway simulation equipment
· Flushing rate calculation formula: [m2/(M-m1)]*100% = flushing rate
The flushing rate is mainly related to the flushing method of the pre-filter, and the flushing method of the five filters mentioned earlier, but considering that the filtration accuracy of the Smith pre-filter is too low, the interception rate tested is too high, so there is no need to participate in the flushing rate test link this time.
How to test the flush rate of the pre-filter?
First of all, we use purified water as the water source, and open the filter screen of five pre-filters respectively to rinse.
It should be noted that among the four pre-filters, Midea, BKA, and Honeywell support the scraping function, of which Midea and BKA need to be manually scraped.
The pre-filter that supports the scraping function is rinsed and scraped, and then the rinsed water is filled with an empty beaker free of impurities, and the flushing valve is closed after a regular rinse of one minute.
The rinsed water is then filtered using a Brinell funnel, and the filtered silica powder is attached to the qualitative filter paper and then put into a blower for drying.
Finally, using a thousandth balance, the dried silica powder is weighed.
After weighing, the silica impurities of the four pre-filters were weighed respectively:
- The weight of silica washed out by BKA is 1.712 grams;
- The weight of Midea's washed silica is 1.762 grams
- Honeywell washed out silica weighs 1.587 grams;
The weight of silica washed out by 3M is 1.304 grams.
The mass of the washed silica impurities is set to m2, combined with the formula [m2/(M-m1)] * 100% = flushing rate, the flushing rate of the four pre-filters is calculated:
- BKA：95.01%
- Midea: 96.81%
- Honeywell: 87.05%
- 3M：73.01%
As far as the calculated flushing rate results are concerned, the rinsing effect of BKA and Midea is very good, among which BKA has the highest flushing rate, and the silica powder on the filter screen can basically be washed out; Midea's flushing performance is also very good, with a flushing rate of 93.74%.
What surprised me was Honeywell's rinsing performance, I thought that it was equipped with a backwash method with automatic scraping, which can have a higher flushing rate, but in fact, the effect of automatic scraping will be slightly inferior to manual scraping, so its rinsing rate will be lower than that of BKA and Midea.
Since the 3M adopts a direct flush type, it is reasonable that it has the lowest flush rate.
5. Disassembly part
It took eighteen martial arts to completely disassemble these five pre-filters.
In terms of the difficulty of disassembly, it is best to disassemble 3M and Smith, because they do not have a shell to cover the filter bottle, and the filter bottle can be separated from the copper head by directly twisting the copper head part of the filter.
In terms of structure, Smith and 3M both put the filter screen directly with a filter bottle, which is relatively simple. Since Smith was not involved in the flush rate test, there was no visible silica residue on its filter.
The 3M uses direct flushing, which also has the lowest flush rate of the four pre-filters.
Therefore, its filter screen is stained with a lot of silica powder, and you can clearly feel the granular feeling of silica by touching the filter part of the 3M pre-filter with your hand.
The Honeywell pre-filter has a shell over the filter bottle, which is easy to disassemble, and after removing the shell, the copper head can be unscrewed with a little force.
Because Honeywell adopts an automatic scraping design, it can be clearly seen that Honeywell's structural design is different from the previous two models.
For the residue of the filter, there is not much silica left on the surface, which is basically invisible to the naked eye, but when touched by hand, you can still feel a certain graininess.
The BKA pre-filter is relatively difficult to remove, its shell is snapped up, you need to use a driver to pry it open, and then unscrew the copper head, and finally take out the filter inside.
As the pre-filter with the highest flushing rate, its filter surface is basically free of silica, and there is no obvious graininess when touched by hand.
Among the five pre-filters, the most difficult to remove.
Although from the perspective of bloggers, the difficulty of beauty is a point of complaining, but from the perspective of consumers, this can also reflect the solid and excellent quality of beauty.
First of all, the shell of the Midea pre-filter is buckled with a snap, and it takes a lot of effort to remove its shell.
I thought that I could easily unscrew the copper head of the filter bottle, but the copper head of the Midea pre-filter could hardly be unscrewed. No way, in order to remove the amount of silica residue in the filter inside the buckle, I had to use a chainsaw to see the filter bottle.
The amount of silica residue in the Midea pre-filter is also very small, and the silica residue cannot be seen with the naked eye, and there is only a fine grainy feeling when touched by hand.
In summary, of the four pre-filters that have been tested for flushing rate, the lowest silica residue is BKA, followed by beauty, Honeywell's silica residue is more obvious, and the silica residue is the most 3M.
Among them, BKA and Midea use manual scraping + backlash design, although Honeywell adopts automatic scraping, but because the scraping speed is not as good as manual, the residual amount of silica will be slightly more obvious than BKA and Midea.
6. Summary of the experience of the five pre-filters
After a month-long evaluation experience, the specific test results are shown in the following figure:
Among the five prefilters, the best comprehensive experience is the Midea frigate prefilter.
Although in a number of tests, Midea has not ranked first, but it has no obvious shortcomings in the comprehensive experience, especially the test part, whether it is the retention rate or the flushing rate, it can achieve a satisfactory level. The two installation methods, horizontal and vertical, also meet the needs of users with different space requirements.
As a higher-priced product, Honeywell also delivers good performance. In addition to the atmospheric design, its automatic flushing function is also convenient. However, it should be noted that although Honeywell's automatic rinsing function supports automatic scraping, it is best to rinse longer to obtain better scraping results.
BKA is more like a partial student, its flush rate is excellent, but its retention rate is average. In addition, its installation angle is diverse, and the copper head angle can be adjusted to meet the installation needs of different angles. However, its volume is large, and for friends who do not have enough space under the kitchen, the choice needs to be cautious.
Classic brands such as Smith and 3M and the like, the core competitiveness of the two is relatively much weaker, and the material used is inferior to the other three, of which Smith's filtration accuracy is only 100μm, and it has not been eliminated by half before the test link, and the overall is more general.