During the warranty period due to a failure of our products appear positive outlet face, and I will be five working days after receiving the notice to the field service until the fault completely ruled out pressure delivery outlet, the product is completely back to normal operation. Stairwell installation height did not explain, from a structural and safety point of view, mounted on top is better, because the stairs are connected across positive outlet quotes, installed where almost; wind speed of not more than 7m / s pressure delivery outlet types , but for the moment this value, the pressure loss is too large, depending on the system resistance Shenyang pressure delivery outlet, rich ventilation equipment (certified), pressure delivery outlet provided by Dezhou Plumper ventilation plant. Dezhou Plumper ventilation plant (www.frtfsb.com) is a leader in Dezhou, fans, ventilation equipment, over the years, the company implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, and satisfy customer needs. Rich ventilation equipment in leadership with the staff warmly welcome all inquiries negotiations to create rich, ventilation a better future.