Uniquely designed top spin bar and bottom valve plate mechanism produces a positive seal for sample retention. This provides excellent control for releasing the sample slowly and accurately into containers. The modular construction adds flexibility by allowing the connection of several sections to form a longer sampling unit; up to a maximum length of 20 feet. Chemically-resistant PVC. Spin open top locking handle. Slowly insert the Coliwasa into a drum or tank to collect liquid column. Pull top handle to seat the valve plate and spin the top locking handle closed to trap column in the sampler. Remove unit from drum or tank and dispense into sample container. All units, including modular extension and connector sets, are supplied with a cleaning brush.