He retired last year after 22 years as a consultant and moved from Springfield to Virginia.
He was a member of the American Institute of Chemical Engineers for 61 years and a longtime member of the American Petroleum Institute, for which he chaired the subcommittee on heat-transfer equipment. In recent years, he had joined the Chemical Consultants Network.
Mr. Conklin was married to Elizabeth Stevens Conklin, known as "Betsy," for 52 years. She died in 2007.
Mr. Conklin was a longtime member of Covenant United Methodist Church in Springfield, where he served as a trustee, Sunday-school teacher, and on the property and memorial garden committees.
He loved the University of Virginia, which he supported as president of the Philadelphia Alumni Chapter and as an interviewer for the Jefferson Scholars Program. He recently attended his 61st class reunion.
Mr. Conklin was a 19-year member and president of the Lions Club in Springfield, for which he managed the eyeglass-collection program. In 2002, the Lions Club International Foundation named him the Melvin Jones Fellow for Dedicated Humanitarian Services.
He and his wife thrived on gardening. They were members of various groups, including the Garden Club of Springfield, the Pennsylvania Horticultural Society, and the American Iris Society. "He had 300 varieties at one point in the yard," said his daughter Linda Walton.
In 2013, Mr. Conklin moved to Greenspring Village, a retirement community in Virginia, to be near family. He delighted in spending time with his grandchildren.
In addition to his daughter, he is survived by two other daughters, Carol and Virginia; two grandchildren; and a nephew.
A memorial service will be held Saturday, June 14, at Covenant United Methodist Church, 212 W. Springfield Rd., Springfield. Visitation will be at 2 p.m., with the service at 3. Interment will be private.
Contributions may be made to the Lions Club International Foundation, Department 4547, Carol Stream, Ill. 60122 or via www.lcif.org/EN/ways-to-give/lion-memory-honor-donation.php.