What is an Airless
SCR System?
E.I. Williams/IMS’ Airless SCR system represents the next generation of Tier 4 Final NOx reduction for stationary and standby power generators. Built without compressed air systems, this compressor-free diesel aftertreatment solution simplifies installation, lowers total cost of ownership, and ensures reliable emissions and acoustic control for diesel and gas-powered engines.
What is SCR?
Selective Catalytic Reduction (SCR) systems reduce nitrogen oxide (NOx) emissions by up to 98% using Diesel Exhaust Fluid (DEF). Once injected into the exhaust stream, DEF transforms into ammonia, which reacts with NOx over the SCR catalyst to form harmless nitrogen and water vapor.
Our Tier 4 Final–compliant SCR systems include
Why Choose Airless Technology?
Unlike traditional SCR systems that require compressed air, Airless SCR operates using airless DEF injection—no compressors, no pneumatic lines.
This means
Compressor-free dosing technology is especially suited for rooftop enclosures, mobile power units, and space-limited mechanical rooms.
Airless VS Standard SCR
Integrated Silencing & DPF Compatibility
Our low noise SCR systems incorporate generator exhaust silencers and DPF-ready designs to meet strict acoustic and particulate regulations
Custom DEF Tank Solutions
We offer turnkey DEF tank packages designed for
Each DEF system includes level sensors, alarms, and appropriate insulation for climate resilience.
Total Cost of Ownership Savings
Airless SCR delivers measurable long-term benefits
Each DEF system includes level sensors, alarms, and appropriate insulation for climate resilience.
Proven Performance in Action
See how E.I. Williams/IMS solutions are deployed in the field — from rooftop enclosures to large-scale generator yards. Our systems are built for versatility, precision, and long-term durability across a wide range of real environments.
