FA813219QA013_Q&A_Amendment_04.pdf

FA813219QA013 Questions and Answers

1. Question: Following Site Visit, it was noted that more locations were shown than what were listed on Appendix A. Are there additional systems?

Answer: Yes. A new Appendix A is included with this amendment

2. Question: What is the average annual (or monthly average based on 12 months of usage) water make-up to each system?

Answer: Sample Water System Analysis Reports are attached to this amendment for clarification.

3. Question: What is the approximate system volume for each system?

Answer:

Appendix A Items 1 & 2- This system consists of two (2) each identical Fluid Coolers OC17692 and OC16520, both manufactured by Baltimore Air Coil (M/N: FXV-364-31R, S/N’s: U053394501 and U053394503), and were purchased/installed circa 1995. Per manufacturer’s literature, each fluid cooler is rated for 579 tons nominal. Each fluid cooler possesses an independent basin (integral to each fluid cooler) for spray bar water; each cooler’s basin holds/maintains approximately 2700 gallons of water. Note that each fluid cooler possesses two (2) coils and two (2) simultaneously operated spray bar motor pumps (one spray bar motor pump per coil), with a single VFD controlled up-flow fan. The fluid coolers are operated in a lead/lag configuration, alternated weekly. The fluid coolers, spray bar motor pumps, and VFD fan cycle on and off (along with speed variation for the fan) per cooling demand. Except for a few weeks during the summer months, one fluid cooler can typically handle the entire cooling load. Each open loop (total of two, one per fluid cooler) portion of this system operates as follows: water is pumped from the basin, runs to the spray bars, flows over the fluid cooler coils, and gravity returns back to the basin. Make-up water is automatically added to each fluid cooler’s basin to compensate for evaporation, drift losses, and blow-down. The closed loop portion of this system operates as follows: water from a “hot” reservoir tank is pumped to each fluid cooler (one motor pump per fluid cooler), runs through the fluid cooler coils, and returns to a “cold” reservoir tank. Then the water from the “cold” reservoir tank is pumped (using a separate set of motor pumps) to the vacuum furnaces (heat load), and is then returned back to the “hot” reservoir tank. The motor pump to the vacuum furnaces continuously flow approximately 2500 GPM. The motor pump to each fluid cooler flow approximately 1400 GPM, so with both fluid coolers in use, the flow through both fluid coolers is approximately 2800 GPM total. The (roughly) estimated total cooling water volume for this closed loop system is circa 20,000 gallons. Make-up water is automatically added to the “cold” sump to make up for evaporation losses.

Appendix A Item 4 - This system consists of one (1) each Fluid Cooler OC13887, manufactured by Recold (M/N: JWH-115C, S/N: 991006), and was purchased/installed circa 2000. Per the manufacturer and literature, the fluid cooler is rated for 175 tons nominal. The fluid cooler possesses a basin (integral to the fluid cooler) for spray bar water; the basin holds/maintains approximately 880 gallons of water. This fluid cooler uses a single spray bar motor pump and single cross-flow fan. The fluid cooler spray bar motor pump and fan cycles on and off per cooling demand.

The open loop portion of this system operates as follows: water is pumped from the basin, runs to the spray bars, flows over the fluid cooler coils, and gravity returns back to the basin. Make-up water is automatically added to the fluid cooler’s basin to compensate for evaporation, drift losses, and blow-down.

The closed loop portion of this system operates as follows: water/glycol solution (30% glycol) from the reservoir tank is pumped to the fluid cooler, runs through the fluid cooler coil, runs to the vacuum furnaces (heat load), and returns back to the reservoir tank. The motor pumps to the fluid cooler (and furnaces) continuously flow approximately 1000 GPM. The total glycol/water solution volume is estimated at 4,500 gallons. Gylcol and/or make-up water is manually added to the reservoir tank, as needed.

Appendix A Item 5 & 6 - This small, closed loop system does not utilize a fluid cooler or cooling tower, but obtains its cooling action from a shell and tube heat exchanger tied-in to the Base Supplied chilled water loop. The system was manufactured from both new and used components, and was installed circa 2003.

This closed loop system operates as follows: water from the reservoir tank is pumped through the tube side heat exchanger (chilled water on the shell side), and is returned back to the reservoir tank. Separate motor pump(s) pull water from the same reservoir tank, runs to the Polycolds (heat load), and is returned back to the reservoir tank. The motor pump to the Polycolds continuously flows between 50 – 100 GPM. The cooling water flow through the (tube side) of the heat exchanger is a maximum 120 GPM; the chilled water flow through the (shell side) of the heat exchanger is a maximum 50 GPM. The total cooling water system fluid volume is circa 1000 gallons. Make-up water is manually added to the reservoir tank, when required

4. Question: The first closed system we looked at was downstairs in a confined entry area. I need to know how chemical is currently added. Dosing pumps? Shot feeder? Etc.

Answer: Only base Civil Engineer (CE) personnel are authorized to enter that space. The chemicals for this system are only for the basin water in the fluid cooler, and dosing pumps (operated by the conductivity controller) are used - those dosing lines are tied-in to a chemical sensing line that runs from the fluid cooler - to the west interior wall, and back to the fluid cooler (the spraybar pump provide the pressure flow), so these tie-in inside the building in the same area that the conductivity controller and chemical storage tanks are located, which are all above grade. Contractor will only test that system’s glycol loop 4 times annually and report the results. If the system’s level gets low on fluid or needed ratio changes, Government personnel will identify the needed quantities of glycol and/or water additions and purchase the propylene glycol, and government pesonnel will add through port to the glycol system (accessible from above the pit opening in the floor grating).

5. Question: Is the contractor responsible for transportation and handling of chemicals?

Answer: The contractor shall bring their vehicle on base with their chemical storage containers, and pump transfer the chemicals from their vehicle to the double-walled containment tanks that are located at each treatment site.

6. Question: Since water sampling was not part of the walkthrough process, can you provide a water analysis report for the make-up water for these systems?

Answer: Sample report is attached to the amendment.