1.
What full-scale flow ranges are available for the mass flow controllers in the Gas Metering unit?
The range and gas for each mass flow controller is specified by the client at the time of order. The full-scale can be chosen as any value between 5 sccm and 100 slpm rated in nitrogen.
|
|
top
|
|
2.
Are the mass flow controllers accurate all the way down to zero flow?
The mass flow controllers are rated for +/- 1% full-scale flow from 2% to 100% of the calibrated full-scale flow. If a wider range is required, multiple mass flow controllers for a single gas may be added for 'range control'. As an example, a 100 lpm mass flow controller is only accurate down to 2 lpm so it may be desirable to also include a 5 slpm mass flow controller in parallel.
|
|
top
|
|
3.
What does the Gas Handling option provide?
The Gas Handling option adds manual backpressure control of the fuel cell exhaust gases and is incorporated with the Mixing unit into a single cabinet in most cases. The downstream gases are routed separately through the Handling section where any entrained water is removed. The trapped water is automatically pumped from the unit as needed. The user can manually adjust the backpressure on the cell up to 50 psi. The pressure is measured and displayed through software as well as on a gauge on the front panel of the unit. Optional differential pressure gauges and transducers are also available to measure the pressure drop on the fuel and/or oxidizer sides from inlet to outlet of the cell. Backpressure dump valves open in the event of a power failure, emergency stop or when the backpressure surpasses a user-specified set point.
|
|
top
|
|
4.
What are the differences between the Gas Metering unit and the Gas Mixing unit?
The Gas Metering unit provides independent metering of up to six gas streams with any combination of fuels and/or oxidizers. For example, a single unit may contain five (5) fuels and one (1) oxidizer. Optional external manifolds allow two or more gas channel outputs to be combined for mixing. Whereas, the Gas Mixing unit is internally manifolded for up to four fuel channels and two oxidizer channels.
In both the Gas Metering and Mixing systems, a fail-safe purge is provided. The purge stream(s) will open in the event of a power failure or low purge gas pressure. Each channel specified as a fuel in the Gas Metering system includes a passive purge stream that engages when the channel is not active. The Gas Mixing system includes a single software controlled fuel purge with user-settable conditions that must be met before the purge will activate.
|
|
top
|
|
5.
What is the purpose of the 'backpressure dump solenoid valves' in the Gas Handling unit?
Each of the two reactant gas streams has a normally open solenoid valve installed to bypass the backpressure regulators in an emergency stop situation. As one example, when the emergency stop button on the front panel is pressed, all of the gas feed valves close and the backpressure dump valves open. This ensures that reactant gas flow to the fuel cell is stopped and backpressure on the fuel cell is relieved.
|
|
top
|
|
6.
Are the backpressure dump solenoid valves only controlled by the front panel emergency stop?
The backpressure dump solenoid valves may also be turned off (i.e., opened) through software. As an example of this, the user may wish to include a watchdog in the control software, such as FCPowerTM software, so that these valves are opened if a specific backpressure, temperature, differential pressure, or any other system parameter is outside of desired limits.
|
|
top
|
|