1) effects of temperature relay: the relay is afraid of the heat element, high temperature can accelerate the relay inside the plastic and insulation materials aging and oxidation and corrosion, the arc of contact difficulties, deterioration of electric parameters, make less reliable. So, keep away from heating element requires the use of relay, and has good airflow.
2) corrosion effect of gases on relay: in place of corrosive gases, alkaline acid gas on the relay very much, especially the corrosion of the contacts and springs very serious, causing bad contact. Some relays used in low power, once the contact corrosion, closed, it can cause poor contact. When using the relay should stay away from the scene, if not, fails check should be preferred.