| Exhibit                (10.ad) |
|--------------------------------|

**FOURTH      AMENDMENT TO THE**

**MET-PRO      CORPORATION SALARIED PENSION PLAN**

| This                Fourth Amendment to the Met-Pro Corporation Salaried Pension Plan                (the                “Plan”) is made by Met-Pro Corporation (the “Company”).**WITNESSETH****WHEREAS**,                the Company established the Plan for its eligible employees effective                as                of September 1, 1968, and amended and restated as of September 1,                2000;                and**WHEREAS**,                the Company reserved the right in Section 16.1 of the Plan to amend                the                Plan at any time; and **WHEREAS**,                the Company now desires to amend the Plan to freeze participation                in the                Plan as to new hires effective as of April 15, 2006.**NOW,                THEREFORE**,                the Plan is hereby amended as set forth below.1.     Section                1.20, Definition of “Eligible Employee” is amended by adding the following                to the end thereof: Notwithstanding the foregoing, an Employee hired                on or                after April 15, 2006 shall not be eligible to participate in the                Plan.2.    Section                2.3 of the Plan is amended by adding the following to the end thereof:                Notwithstanding the foregoing, an Employee hired on or after April                15,                2006 shall not be eligible to participate in the Plan.**IN                ALL OTHER RESPECTS**,                this Plan is continued in full force and effect. In order to maintain                the                terms of the Plan in a single document, this Amendment may be incorporated                into the most recent restatement of the Plan.**IN                WITNESS WHEREOF**,                the Company has caused this Fourth Amendment to be executed by its                duly                authorized officer this 5th day of April,                2006. |
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|        |                            |                                   |   |                                |   |      |
|-------------|---------------------------------|----------------------------------------|--------|-------------------------------------|--------|-----------|
| **ATTEST:** |                            | **Met-Pro                Corporation** |
|        |                            |                                   |   |                                |   |      |
| By          | /s/              Gary J. Morgan |                                   | By     | /s/              Raymond J. De Hont |
|        |                            |                                   |   |                                |   |      |
| Title:      |                            | Vice                President-Finance  |   | Title:                              |   | President |