- Quantitative analysis
- Low ash content 0.007% (Acid-wash treated)
- High wet-strength
- Consistent performance
- Hardened grades available
- Custom cut
- Bulk packaging
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These standard ashless grades are high purity filter papers suitable for routine quantitative gravimetric
techniques and in the preparation of samples for use in analysis involving instrumental techniques.
- Ahlstrom 94: 1.5μm – Slow Speed
This is an extremely fine retention filter for critical
gravimetric analysis of very fine particles such as
barium and lead sulfates, stannic and nickel sulfide,
calcium oxalate and calcium fluoride.
- Ahlstrom 74: 2.0μm – Medium Speed
This grade has medium flow rate and good particle
retention and is the most commonly used acidwashed
filter. Ahlstrom 74 covers a wide range of
general ashless filtration applications. It is used for
gravimetric analysis of numerous components (e.g.:
cements, copper, clay, bismuth, silicon, iron) found in
heavy industries such as construction, mining or
steel. Ahlstrom 74 is also used as a high purity filter
for speedy filtering of trace elements such as silver
chromate, lead sulfate, zinc and ammonium
hydroxides. Ahlstrom 74 is also found in general soil
analysis for separating solid from aqueous extracts.
- Ahlstrom 54: 10μm – Fast Speed
This is a fast filtering grade for rapid filtration of
coarse particles and gelatinous precipitates such as
iron, zirconium and aluminum hydroxides, and cobalt
sulfide. Ahlstrom 54 is also used in air pollution
testing to determine gaseous compounds. It is
recommended for fast analysis procedures for
unstable precipitates such as silicon, which requires
speedy filtration.
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These specially treated hardened ashless grades are available for critical quantitative analytical
techniques requiring increased wet-strength and handling capacity. These high purity filter papers have
a tough, smooth surface free of loose fibers and are ideal for collecting wet precipitates. Each grade
offers a convenient combination of particle retention and flow rate and are generally used because of
their high chemical resistance to strong acid and alkali.
- Ahlstrom 95: 1.5μm – Slow Speed
This is an extremely fine retention filter for critical
gravimetric analysis and metal determination of very
fine particles such as barium and lead sulfates,
stannic and nickel sulfide, calcium oxalate and
calcium fluoride.
- Ahlstrom 75: 2.0μm – Medium Speed
This grade has medium flow rate and good particle
retention and is most commonly used for
applications requiring high chemical resistance to
strong acid and alkali. Ahlstrom 75 is often used for
filtering trace elements, collecting hydroxides after
precipitation by strong alkalis and in the analysis of
metals in acid and alkali solutions.
- Ahlstrom 55: 15μm – Fast Speed
This is a fast filtering grade for gravimetric analysis of
coarse particles and gelatinous precipitates (i.e.:
aluminum and zirconium hydroxides) in acid and
alkali solutions. Ahlstrom 55 is also used in air and
foodstuffs analysis and for chloride and phosphorous
in cement, coal and coke.
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| Grades |
Retention in µm |
Filtration Speed
Herzberg sec/100mls |
Filtration Speed
Rapidity mls/min |
Loading
capacity |
Whatman Cross
Reference |
| 94 |
1.5 |
1724 |
4 |
Medium |
42 |
| 74 |
2.0 |
229 |
30 |
Medium |
40 |
| 54 |
10.0 |
34 |
200 |
Medium |
41 |
| 95 |
1.5 |
458 |
15 |
Medium |
542 and 50 |
| 75 |
2.0 |
149 |
45 |
Medium |
540 and 52 |
| 55 |
15.0 |
31 |
220 |
Medium |
541 and 54 |
| (100 circles/box) |
| Size* |
54 |
55 |
74 |
75 |
94 |
95 |
| 4.25 |
0540-0425 |
0550-0425 |
0740-0425 |
0750-0425 |
0940-0425 |
0950-0425 |
| 5.5 |
0540-0550 |
0550-0550 |
0740-0550 |
0750-0550 |
0940-0550 |
0950-0550 |
| 7.0 |
0540-0700 |
0550-0700 |
0740-0700 |
0750-0700 |
0940-0700 |
0950-0700 |
| 9.0 |
0540-0900 |
0550-0900 |
0740-0900 |
0750-0900 |
0940-0900 |
0950-0900 |
| 11.0 |
0540-1100 |
0550-1100 |
0740-1100 |
0750-1100 |
0940-1100 |
0950-1100 |
| 12.5 |
0540-1250 |
0550-1250 |
0740-1250 |
0750-1250 |
0940-1250 |
0950-1250 |
| 15.0 |
0540-1500 |
0550-1500 |
0740-1500 |
0750-1500 |
0940-1500 |
0950-1500 |
| 18.5 |
0540-1850 |
0550-1850 |
0740-1850 |
0750-1850 |
0940-1850 |
0950-1850 |
| 24.0 |
0540-2400 |
0550-2400 |
0740-2400 |
0750-2400 |
0940-2400 |
0950-2400 |
| 27.0 |
0540-2700 |
0550-2700 |
0740-2700 |
0750-2700 |
0940-2700 |
0950-2700 |
| 32.0 |
0540-3200 |
0550-3200 |
0740-3200 |
0750-3200 |
0940-3200 |
0950-3200 |
| 40.0 |
0540-4000 |
0550-4000 |
0740-4000 |
0750-4000 |
0940-4000 |
0950-4000 |
| * All circle diameters are in centimeters |
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