EXHIBIT 99-B



                            CERTIFICATION PURSUANT TO
                               18 U.S.C. SS. 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002


In connection with the Annual Report of Donaldson Company, Inc. (the "Company")
on Form 10-K for the period ended July 31, 2002 as filed with the Securities and
Exchange Commission on the date hereof (the "Report"), I, William G. Van Dyke,
Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. ss.1350,
as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

         1.       The Report fully complies with the requirements of Section
                  13(a) or 15(d) of the Securities Exchange Act of 1934; and

         2.       The information contained in the Report fairly presents, in
                  all material respects, the financial condition and results of
                  operations of the Company.



                                        /s/ William G. Van Dyke
                                        ----------------------------------------
                                        William G. Van Dyke
                                        Chief Executive Officer
                                        October 28, 2002