<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<RESTATED>
<CIK> 0000861184
<NAME> WAHLCO ENV. SYSTEMS
<MULTIPLIER> 1,000

<S>                             <C>                     <C>                     <C>
<PERIOD-TYPE>                   3-MOS                   6-MOS                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1997             DEC-31-1997
<PERIOD-END>                               MAR-31-1997             JUN-30-1997             SEP-30-1997
<CASH>                                           2,261                   2,049                   2,014
<SECURITIES>                                         0                       0                       0
<RECEIVABLES>                                   14,345                  12,114                   9,749
<ALLOWANCES>                                         0                       0                       0
<INVENTORY>                                      4,254                   4,374                   4,731
<CURRENT-ASSETS>                                23,926                  22,534                  21,286
<PP&E>                                           4,933                   4,777                   4,601
<DEPRECIATION>                                       0                       0                       0
<TOTAL-ASSETS>                                  30,088                  28,605                  27,095
<CURRENT-LIABILITIES>                           18,683                  17,313                  17,166
<BONDS>                                              0                       0                       0
<PREFERRED-MANDATORY>                                0                       0                       0
<PREFERRED>                                          0                       0                       0
<COMMON>                                           176                     176                     176
<OTHER-SE>                                     (3,482)                 (3,811)                 (5,336)
<TOTAL-LIABILITY-AND-EQUITY>                    30,088                  28,605                  27,095
<SALES>                                         11,357                  23,808                  32,730
<TOTAL-REVENUES>                                12,734                  26,796                  37,548
<CGS>                                            9,116                  19,063                  26,313
<TOTAL-COSTS>                                    9,983                  20,978                  29,672
<OTHER-EXPENSES>                                 2,977                   5,969                   9,023
<LOSS-PROVISION>                                     0                       0                       0
<INTEREST-EXPENSE>                               (426)                   (895)                 (1,366)
<INCOME-PRETAX>                                  (604)                   (994)                 (2,445)
<INCOME-TAX>                                         0                       0                       0
<INCOME-CONTINUING>                              (604)                   (994)                 (2,445)
<DISCONTINUED>                                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0
<CHANGES>                                            0                       0                       0
<NET-INCOME>                                     (604)                   (994)                 (2,445)
<EPS-PRIMARY>                                   (0.03)                  (0.06)                  (0.14)
<EPS-DILUTED>                                   (0.03)                  (0.06)                  (0.14)


</TABLE>