<PAGE>

                                                                    EXHIBIT 31.2

                    CERTIFICATION PURSUANT TO RULE 13a-14(a)
                             CHIEF FINANCIAL OFFICER

I, Daniel C. Dunn, Vice President-Finance and Chief Financial Officer of Allied
Healthcare Products, Inc., certify that:

      1. I have reviewed this quarterly report on Form 10-Q of Allied Healthcare
      Products, Inc.;

      2. Based on my knowledge, this quarterly report does not contain any
      untrue statement of a material fact or omit to state a material fact
      necessary to make the statements made, in light of the circumstances under
      which such statements were made, not misleading with respect to the period
      covered by this report;

      3. Based on my knowledge, the financial statements, and other financial
      information included in this annual report, fairly present in all material
      respects the financial condition, results of operations and cash flows of
      the registrant as of, and for, the periods presented in this report;

      4. The registrant's other certifying officers and I are responsible for
      establishing and maintaining disclosure controls and procedures (as
      defined in Exchange Act Rules 13a-15(e)) and internal control over
      financial reporting (as defined in Exchange Act Rules 13a-15(f)) for the
      registrant and have:

      a) designed such disclosure controls and procedures, or caused such
      disclosure controls and procedures to be designed under our supervision,
      to ensure that material information relating to the registrant, including
      its consolidated subsidiaries, is made known to us by others within those
      entities, particularly during the period in which this report is being
      prepared;

      b) [not applicable to this reporting period since registrant is not an
      accelerated filer];

      c) evaluated the effectiveness of the registrant's disclosure controls and
      procedures and presented in this report our conclusions about the
      effectiveness of the disclosure controls and procedures as of the end of
      the period covered by this report; and

      d) disclosed in this report any change in the registrant's internal
      control over financial reporting that occurred during the registrant's
      most recent fiscal quarter (the registrant's fourth quarter in the case of
      an annual report) that has materially affected, or is reasonably likely to
      materially affect, the registrant's internal control over financial
      reporting; and

      5. The registrant's other certifying officers and I have disclosed, based
      on our most recent evaluation of internal control over financial
      reporting, to the registrant's

<PAGE>

      auditors and the audit committee of registrant's board of directors (or
      persons performing the equivalent functions):

      a) all significant deficiencies and material weaknesses in the design or
      operation of internal control financial reporting which are reasonably
      likely to adversely affect the registrant's ability to record, process,
      summarize and report financial information; and

      b) any fraud, whether or not material, that involves management or other
      employees who have a significant role in the registrant's internal
      controls over financial reporting.

                                      Date: November 5, 2004

                                      /s/ Daniel C. Dunn
                                      -------------------------
                                      Daniel C. Dunn,
                                      Vice President and Chief Financial Officer