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