Abstract: The invention provides for a roofing membrane tensioner 10 having a base 102 with a hook 36 for catching the edge 22 of an underlying surface 20, a membrane connector 108, and a means for moving the membrane connector towards the edge by applying force inwardly 24 from the edge. The means for moving the membrane connector towards the edge can be a lever 104 operated substantially in the same plane as the underlying surface. The force can be applied at least 50 cm from the edge. The base can have a flat side and a hook side. The base can also have a mount 110 for connecting the lever. The mount can be the fulcrum 110 for the lever.

Abstract: A re-usable piston filter including an elongated tubular barrel member with a closed lower end and an open upper end, an elongated tubular piston member having an open upward end and a fluid-permeable lower end, and filter means detachably secured to the lower end of the piston. Downward movement of the piston in the barrel forces liquid in the barrel through the filter and into the tubular piston. An air valve in the barrel can be opened to enable the piston to be withdrawn from the barrel. The filter at the lower end of the piston can be changed or removed as desired.

Abstract: A method for determining trace amounts of total chlorine present in a water sample. The method includes use of DPD as an indicator. The sample is filtered after a color development delay, and then light absorbance through the sample is measured. A control sample is treated with malonic acid to de-chlorinate the control. Light absorbance through the sample being tested is adjusted by the light absorbance through the control sample.