Exhibit 5.1

December 1, 2010

IDEX Corporation
1925 West Field Court
Lake Forest, Illinois 60045

     Re:       Registration Statement on Form S-3

233 S. Wacker Drive, Suite 5800
Chicago, Illinois 60606
Tel: +1.312.876.7700 Fax: +1.312.993.9767
www.lw.com
FIRM / AFFILIATE OFFICES
Abu Dhabi	Moscow
Barcelona	Munich
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Frankfurt	Rome
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Hong Kong	San Francisco
Houston	Shanghai
London	Silicon Valley
Los Angeles	Singapore
Madrid	Tokyo
Milan	Washington, D.C.

Ladies and Gentlemen:

     We have acted as special counsel to IDEX Corporation, a Delaware corporation (the “Company”), in connection with the Company’s filing on the date hereof with the Securities and Exchange Commission (the “Commission”) of a registration statement on Form S-3 (the “Registration Statement”) under the Securities Act of 1933, as amended (the “Act”), relating to the registration for issue and sale by the Company of one or more series of the Company’s debt securities (collectively, the “Debt Securities”) to be issued pursuant to an indenture by and among the Company, as issuer and Wells Fargo Bank, National Association, as trustee (the “Trustee”), in the form included as Exhibit 4.1 to the Registration Statement, as such indenture may be supplemented from time to time (the “Indenture”).

     This opinion is being furnished in connection with the requirements of Item 601(b)(5) of Regulation S-K under the Act, and no opinion is expressed herein as to any matter pertaining to the contents of the Registration Statement or related prospectus, other than as expressly stated herein with respect to the issue of the Debt Securities.

     As such counsel, we have examined such matters of fact and questions of law as we have considered appropriate for purposes of this letter. With your consent, we have relied upon certificates and other assurances of officers of the Company and others as to factual matters without having independently verified such factual matters. We are opining herein as to the internal laws of the State of New York, and we express no opinion with respect to the applicability thereto, or the effect thereon, of the laws of any other jurisdiction or as to any matters of municipal law or the laws of any local agencies within any state.

     Subject to the foregoing and the other matters set forth herein, it is our opinion that, as of the date hereof, when the Indenture has been duly authorized by all necessary corporate action of the Company and duly executed and delivered, and when the specific terms of a particular series of Debt Securities have been duly established in accordance with the terms of the Indenture authorized by all necessary corporate action of the Company, and such Debt Securities have been duly executed, issued and authorized in accordance with the Indenture and in the manner contemplated by the Registration Statement and/or the applicable prospectus and by such

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corporate action, such Debt Securities will be the legally valid and binding obligations of the Company, enforceable against the Company in accordance with its terms.

     Our opinions are subject to: (i) the effect of bankruptcy, insolvency, reorganization, preference, fraudulent transfer, moratorium or other similar laws relating to or affecting the rights and remedies of creditors; (ii) the effect of general principles of equity, whether considered in a proceeding in equity or at law (including the possible unavailability of specific performance or injunctive relief), concepts of materiality, reasonableness, good faith and fair dealing, and the discretion of the court before which a proceeding is brought; (iii) the invalidity under certain circumstances under law or court decisions of provisions providing for the indemnification of or contribution to a party with respect to a liability where such indemnification or contribution is contrary to public policy; and (iv) we express no opinion as to (a) any provision for liquidated damages, default interest, late charges, monetary penalties, make-whole premiums or other economic remedies to the extent such provisions are deemed to constitute a penalty, (b) consents to, or restrictions upon, governing law, jurisdiction, venue, arbitration, remedies, or judicial relief, (c) waivers of rights or defenses, (d) any provision requiring the payment of attorneys’ fees, where such payment is contrary to law or public policy, (e) any provision permitting, upon acceleration of any Debt Security, collection of that portion of the stated principal amount thereof which might be determined to constitute unearned interest thereon, (f) advance waivers of claims, defenses, rights granted by law, or notice, opportunity for hearing, evidentiary requirements, statutes of limitation, trial by jury or at law, or other procedural rights, (g) waivers of broadly or vaguely stated rights, (h) provisions for exclusivity, election or cumulation of rights or remedies, (i) provisions authorizing or validating conclusive or discretionary determinations, (j) grants of setoff rights, (k) proxies, powers and trusts, (l) provisions prohibiting, restricting, or requiring consent to assignment or transfer of any right or property, and (m) the severability, if invalid, of provisions to the foregoing effect.

     With your consent, we have assumed (i) that the Debt Securities and the Indenture governing such Debt Securities (collectively, the “Documents”) will be duly authorized, executed and delivered by the parties thereto, (ii) that each of the Documents will constitute legally valid and binding obligations of the parties thereto other than the Company, enforceable against each of them in accordance with their respective terms, and (iii) that the status of each of the Documents as legally valid and binding obligations of the parties will not be affected by any (a) breaches of, or defaults under, agreements or instruments, (b) violations of statutes, rules, regulations or court or governmental orders, or (c) failures to obtain required consents, approvals or authorizations from, or make required registrations, declarations or filings with, governmental authorities.

     This opinion is for your benefit in connection with the Registration Statement and may be relied upon by you and by persons entitled to rely upon it pursuant to the applicable provisions of the Act. We consent to your filing this opinion as an exhibit to the Registration Statement and to the reference to our firm contained in the Prospectus under the heading “Legal Matters.” In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Commission thereunder.

Very truly yours,
 

/s/ Latham & Watkins LLP