BUSINESS SEGMENTS AND OTHER INFORMATION (Details) (USD $)
 3 Months Ended 12 Months Ended
Jan. 31, 2013
Oct. 31, 2012
Jul. 31, 2012
Apr. 30, 2012
Jan. 31, 2012
Oct. 31, 2011
Jul. 31, 2011
Apr. 30, 2011
Jan. 31, 2013
Jan. 31, 2012
Jan. 31, 2011
Segment Reporting Information [Line Items]                      
Number of operating segments                 5    
Number of Reportable Segments                 3    
Net sales $ 26,976,263 $ 29,761,356 $ 27,997,242 $ 25,207,061 $ 28,397,015 $ 25,245,131 $ 23,089,343 $ 23,429,903 $ 109,941,922 $ 100,161,392 $ 88,865,426
Income from operations                 11,877,811 10,591,284 8,970,321
Depreciation and amortization expense                 2,022,450 1,914,418 1,824,685
Capital expenditures                 1,997,489 2,097,234 1,665,949
Identifiable assets 116,255,181       115,509,215       116,255,181 115,509,215 108,046,328
UNITED STATES [Member]
                      
Segment Reporting Information [Line Items]                      
Net sales                 79,306,963 72,180,541 66,459,905
Income from operations                 8,625,080 8,042,360 7,305,971
Identifiable assets 103,902,569       104,812,114       103,902,569 104,812,114 97,875,243
Foreign [Member]
                      
Segment Reporting Information [Line Items]                      
Net sales                 30,634,959 27,980,851 22,405,521
Income from operations                 3,252,731 2,548,924 1,664,350
Identifiable assets 12,352,612       10,697,101       12,352,612 10,697,101 10,171,085
Product Recovery/Pollution Control Technologies [Member]
                      
Segment Reporting Information [Line Items]                      
Net sales                 49,061,038 43,568,042 41,426,858
Income from operations                 1,033,954 1,198,674 2,046,716
Depreciation and amortization expense                 731,742 708,507 657,724
Capital expenditures                 953,861 692,383 305,803
Identifiable assets 37,932,865       36,444,763       37,932,865 36,444,763 34,003,251
Product Recovery/Pollution Control Technologies [Member] | Foreign [Member]
                      
Segment Reporting Information [Line Items]                      
Net sales                 8,646,957 7,492,321 7,912,462
Fluid Handling Technologies [Member]
                      
Segment Reporting Information [Line Items]                      
Net sales                 37,693,475 33,264,149 27,488,559
Income from operations                 9,959,229 8,220,768 5,926,592
Depreciation and amortization expense                 779,865 720,841 672,072
Capital expenditures                 363,140 580,354 476,104
Identifiable assets 20,093,881       19,290,035       20,093,881 19,290,035 18,114,257
Fluid Handling Technologies [Member] | Foreign [Member]
                      
Segment Reporting Information [Line Items]                      
Net sales                 11,781,689 10,072,782 7,086,069
Mefiag Filtration Technologies [Member]
                      
Segment Reporting Information [Line Items]                      
Net sales                 12,975,840 12,945,610 9,897,038
Income from operations                 805,932 780,586 401,695
Depreciation and amortization expense                 293,604 265,192 265,261
Capital expenditures                 299,801 420,186 138,384
Identifiable assets 15,643,078       14,017,572       15,643,078 14,017,572 12,814,143
Mefiag Filtration Technologies [Member] | Foreign [Member]
                      
Segment Reporting Information [Line Items]                      
Net sales                 10,106,050 10,290,964 7,310,354
Filtration/Purification Technologies [Member]
                      
Segment Reporting Information [Line Items]                      
Net sales                 10,211,569 10,383,591 10,052,971
Income from operations                 78,696 391,256 595,318
Depreciation and amortization expense                 217,239 219,878 229,628
Capital expenditures                 34,951 110,886 57,679
Identifiable assets 8,011,212       8,368,652       8,011,212 8,368,652 8,369,385
Filtration/Purification Technologies [Member] | Foreign [Member]
                      
Segment Reporting Information [Line Items]                      
Net sales                 100,263 124,784 96,636
Total Operating Segments [Member]
                      
Segment Reporting Information [Line Items]                      
Capital expenditures                 1,651,753 1,803,810 977,970
Identifiable assets 81,681,036       78,121,022       81,681,036 78,121,022 73,301,036
Corporate [Member]
                      
Segment Reporting Information [Line Items]                      
Capital expenditures                 345,736 293,424 687,979
Identifiable assets $ 34,574,145       $ 37,388,193       $ 34,574,145 $ 37,388,193 $ 34,745,292