Chandler Engineering is the world's largest supplier of instruments for testing oil, gas and geothermal well cements. From our headquarters in Tulsa, Oklahoma, U.S.A., we design, manufacture, service and support the instruments used for testing per American Petroleum Institute (API) Specification 10 and ISO CD10426. We also provide instruments for API Specification 13 for drilling mud, and API Specification 39 for fracturing fluids.