About Cal Check
About Cal Check
More than 40 years of precision filter certification — now under new ownership, with the same commitment to quality.
Honoring Our History
After more than 40 years of building and operating Cal Check, John Rosenquest has sold the company to Kieth Boyd. John and his wife, Eileen, are looking forward to retirement, with heartfelt appreciation for the customers who have supported Cal Check over the years.
John built Cal Check through technical expertise, personal service, and a commitment to dependable results. His work in opacity monitor testing, filter certification, equipment development, and customer training established a company that customers have trusted for decades. We are proud to carry that legacy forward.
Founder
John Rosenquest's Contributions and Credentials
During his leadership, John served customers across all 50 states and several countries. He developed test equipment and test filters for opacity monitors and trained source operators and state agency personnel to perform opacity audits.
John also worked with consultants, opacity equipment vendors, and regulators on the development of opacity regulations. He earned a master's degree in Environmental Science and Engineering from Virginia Tech.
His expertise, dedication, and lasting customer relationships remain an important part of Cal Check's history.
New Owner
Meet Kieth Boyd
Kieth is a Senior Electrical Engineer with more than 20 years of engineering and technical experience. His career spans highly regulated industries where accuracy, quality, documentation, and reliability are essential. He brings experience managing complex technical projects, working to industry standards, and delivering dependable results for customers.
As Cal Check's new owner, Kieth is committed to maintaining the quality, service, and integrity that John established. Cal Check will continue providing opacity and PM filters, testing equipment, and NIST-traceable filter testing and certification services.
Kieth looks forward to building relationships with longtime customers and welcoming new customers to Cal Check.
John, thank you for trusting me to carry Cal Check forward and for your guidance during this transition. Your commitment to your customers has created a legacy I am proud to continue. I wish you and Eileen a wonderful retirement.
— Kieth Boyd, Owner
Why Clients Trust Cal Check
NIST-Traceable Results
All certifications use measurements traceable to National Institute of Standards and Technology (NIST) reference materials.
40+ Years of Expertise
Cal Check has served customers across all 50 states and several countries since its founding by John Rosenquest.
Standards Compliance
Cal Check meets PS1 Requirements (ASTM D6216-03) and helps facilities comply with emissions regulations.
Experienced New Ownership
New owner Kieth Boyd brings 20+ years of engineering experience in highly regulated industries, ensuring continuity of quality and service.
Discuss Your Recertification Needs
Contact Cal Check to learn how we can support your annual filter certification program.