Environmental sensors for gas composition analysis based on sound velocity measurement are simple, inexpensive and robust. Many potential applications have been outlined in literature, ranging from monitoring CO₂ content in breathing apparatus, composition monitoring of anesthesia gas mixtures [1] to various leak detectors aimed at improving workplace safety [2]. The sensors can be in form of industrial instruments, small IoT (Internet of Things) sensors or wearable MEMS (Micro-Electro-Mechanical Systems) based devices. Such sensors would be of no use without reliable models and algorithms for sound velocity prediction, which are accurate and easy to implement. This work aims to give an overview of technology available to construct speed-of-sound based sensors for industrial applications such as environmental monitoring, leak detection. We are involved in development and deployment of sensors for various applications at CERN (The European Organization for Nuclear Research, Geneva, Switzerland).