Learning Objectives. History of Vacuum Testing for Precast. Vacuum Testing. Terminology and purpose

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1 : It Just Sucks! Presented by: Darryl Cloud Concrete Sealants, Inc. Learning Objectives In this course, you will learn: Terminology for Watertightness Equipment Tips, Tricks, and FAQ s History of Vacuum Testing for Precast Manufacturers of products depend on a number of quality control methods to ensure performance. One method available to the manufacturers of concrete products is vacuum testing. Vacuum testing is an easy and quick method of offering a high degree of reasonableness to the quality, watertighness, and structural integrity to a host of products of varying geometrical configurations. Not that long ago Effective August 1,1960 Deduct $15.00 if Ordered without bottom Terminology and purpose NPCA 1

2 Terminology Definition of a vacuum: According to the definition of the American Vacuum Society (1958) the term "vacuum" refers to a given space filled with gas at pressures below atmospheric. In other words, a vacuum is the state of a gas where the density of the particles is lower than atmospheric pressure at the earth's surface. Terminology Inches of Mercury (in/hg) This is a unit of measure for pressure; it is the measure used by most barometers to measure atmospheric pressure Negative Pressure A pressure that is less than atmospheric, also referred to as a vacuum Watertight Construction such that water cannot pass through except under significant pressure Low Pressure System Vacuum Conversion 1000 = 1 bar = Hg So Why Vacuum Test? To eliminate: Structures: Vacuum testing is performed on: Septic Tanks Manholes Pipe NPCA 2

3 Purpose: Because it improves the seal! Before Vacuum After Vacuum Purpose! Vacuum Force ASTM Specification References C 1214 Concrete Pipe Sewer lines (Field) C 1227, Section 9 Proving water tightness in septic tanks (Plant) C 1244 Concrete Sewer Manholes (Field) C 1618 Concrete Sanitary Sewer Pipe (Plant) Performance Test Methods Test procedures should be clearly defined prior to tank fabrication and installation... Consideration should be given to whether tests will be conducted in the plant or on-site (prior to or after backfilling). ASTM C-1227: Section Vacuum Testing Seal the empty tank and apply a vacuum to 4 inches (100MM) of mercury. The tank is approved if 90% of vacuum is held for 2 minutes. NPCA Best Practice Manual: Introduce a vacuum of 4 inches of mercury. Hold this pressure for five minutes. The tank must have no loss of pressure during the duration of the test. NPCA 3

4 The Precast Show 2014 Alternative Materials Verifying Watertightness in wastewater tanks Orenco literature states that tanks should always be water tested Note: Vacuum testing is not acceptable, as it will not adequately test the flange joint and will not easily reveal very small leaks or leaks created by capillary action. (Orenco assembly instructions NIN-TNK-4) Septic tanks can be tested for water tightness using: The water method Negative pressure / vacuum method WATERTEST vs. VACUUM TEST This is rhetoric! Let see why. Watertight Testing Water Water Column Water Test per ASTM C 1227 Fill tank to the invert of the outlet Let stand for 24 hours Refill the tank Tank passes if water level does not drop within 1 hour ' The force of water is a linear relationship to the height of the column. The force increases by psi per foot. STANDPIPE ' ' ' Local Code Requirement Fill the tank completely into the riser ' 13 30' Hydrostatic Cautions Before Vacuum 1 of water into the riser creates 62 lb/ft2 of lift this will displace a top seal lid Use additional weight when necessary Don t do it if you don t have to! NPCA Before Vacuum A vacuum pulls After thevacuum same at all heights After Vacuum Vacuum Force Vacuum Force ~26 Hg ~30 Hg 4

5 Draw a vacuum on the tank of 4 + Hg Allow tank to settle Return vacuum to 4 Hg Shut valve and hold the vacuum Tank is watertight if there is no loss of vacuum after 5 minutes Watertight Testing: In Field Verifying Watertightness in manholes / pipe Watertight Testing In Plant Manholes and Pipe can be tested for water tightness in the plant with automated equipment. Watertight Testing In Field Manholes and Pipe can be tested for water tightness in the field using a vacuum pump or venturi. NPCA 5

6 Minimum Test Times C a Diameter (in) Depth Time (s) Caution!!!! The negative internal pressure may cause the casting to implode. Alternative Materials This imploded at 11.5 of Hg (800 lb/ft 2 ) Orenco brags about this!!! In there literature, they state that this is substantially higher than the worst-case load =094e0b5cb1b01d712f70 Equipment Vacuum Test Equipment Cherne Vacuum Test Equipment Plug-It NPCA 6

7 Equipment Home made Equipment Alternatives Tips and tricks 1. Use the rubber gasket as supplied 2. Us a small diameter of butyl sealant 3. Use a metal vacuum test lid w/ foam NPCA 7

8 1. Duct tape yea, it can be used for everything! 2. External Joint Warp 3. Expansion pipe plugs 1. Listen shhhh! You ll hear the hissing. 2. Use a power audio detection device. 3. Use water / soapy water 1. Cement slurry 2. Caulking 3. Epoxy sealers 4. Butyl sealant / butyl wrap NPCA 8