Abstract: Provided is a fan filter unit with which the performance of a HEPA filter can be measured at multiple points with ease and in a short time. The fan filter unit has a first HEPA filter, a second HEPA filter, and exhaust means installed between the first HEPA filter and the second HEPA filter. The first HEPA filter, the second HEPA filter, and the exhaust means are integrated by a housing.

Abstract: A housing configuration includes a filter chamber having a purifying filter, a rear chamber in the back, and a fan chamber having a fan. In this housing configuration, a measurement port for purifying filter performance evaluation is provided in a substantially middle portion of the rear chamber, and a connecting portion connected to the measurement port and a cover for maintenance work are provided on the front surface of the housing. Provided as a result is an air purifying negative pressure device that is compact in configuration, can be installed with ease, and is capable of improving both the accuracy of an air purifying filter performance evaluation test and the workability of routine maintenance.

Abstract: Provided is a fan filter unit with which the performance of a HEPA filter can be measured at multiple points with ease and in a short time. The fan filter unit has a first HEPA filter, a second HEPA filter, and exhaust means installed between the first HEPA filter and the second HEPA filter. The first HEPA filter, the second HEPA filter, and the exhaust means are integrated by a housing.

Abstract: Fluid flowmeter, air conditioning system and method of controlling the air conditioning system which includes a Karman vortex generator, ultrasonic transmitter and receiver apparatus and networks for detecting the Karman vortices and for detecting and controlling information of a received wave and a reference wave of the ultrasonic transmitter. The flowmeter detects an air flow volume and/or speed by Karman vortex detecting means using ultrasonic waves. The air conditioning system utilizes the fluid flowmeter for measuring air flow volume and/or flow speed in a duct between an air conditioning apparatus and a chamber to control air flow volume in response to information from the flowmeter.

Abstract: Fluid flowmeter which includes a Karman vortex generator, ultrasonic transmitter and receiver apparatus and networks for detecting the Karman vortices and for detecting and controlling information of a received wave and a reference wave of the ultrasonic transmitter. The flowmeter detects an air flow volume and/or speed by Karman vortex detecting means using ultrasonic waves.