How to get info regarding hardware details

Lots of people ask

Is there a way to detect the number of RAM slots available on my laptop, and the number that are presently occupied, without opening the laptop?

Use CPU-Z. It will give you the CPU, memory details etc, how many RAM slots are left, how much RAM is installed in each slot.

Or you may install SIW. Download the free version, it is good enough. I prefer SIW to CPU-Z. SIW even provides the info on the maximum RAM supported by the motherboard/chipset.

reverse and direct acting controllers

Reverse and direct acting actions for a controller is really confusing. Most of the definitions we hear from chemical engineers are wrong. It is not as simple as

• If an increase in the process variable (increase in devation from setpoint) results in an increase in output (Electric signal or Instrument air flow) , the controller is direct acting.
• If an increase in the process variable results in a decrease in output, the controller is reverse acting.

We need to take into consideration the controller action, i.e. whether it is fail close or fail open. The above definition will hold good for fail close (air to open). It is the opposite for fail safe open (air to close) controllers.

Direct acting means increase in process variable will increase in controller output and visa versa. And opening and closing of valve will depend on valve type AFC (Air fail - CLOSE) or AFO. (AFO valve normally use for cooling water, antisurge valve etc.)


So we can conclude,

• If the PV is increased and the air to controller is also increased, then the controller is direct acting.
• If the PV is increased and the air to controller is decreased, then the controller is reverse acting.

More details about controller actions can be found here.

How to make scanned pdf searchable

Instructions are here.

Can firefox sync chrome bookmarks

Xmark is the tool you're looking for. I haven't used this product. But will try to use sometime later.

Microsoft Excel yes no drop down list

1. Select your range, then go to Data menu --> Validation

2. Select the Settings tab, in the Allow field, select List, then in Source type

Yes,No (without spaces).

You are set to go.

Now if you want to count those Yes or No, use

=countif([Range of Cells], "Yes")

Flare back pressure definitions

Constant back pressure (= constant portion of superimposed backpressure): This back pressure is due to fixed components in the flare header (valves, fittings, pipe etc).

Superimposed back pressure - variable: This is the pressure in the flare header due to the flow from other PSVs into the flare header. For an atmospheric discharge it would be 0 psig.

API definition for superimposed backpressure
The static pressure that exists at the outlet of a pressure relief device at the time the device is required to operate.
Superimposed backpressure is the result of pressure in the discharge system coming from other sources and may be
constant or variable.

Superimposed backpressure (constant + variable) is that backpressure that may exist before opening of the device.

Variable back pressure (built-up back pressure): This is the back pressure that is caused by the flow of liquid to be relieved. This is related to the pressure drop due to the release of the particular PSV.

API definition for built-up backpressure

The increase in pressure at the outlet of a pressure relief device that develops as a result of flow after the pressure relief device opens.

(Total) Back pressure
The pressure that exists at the outlet of a pressure relief device as a result of the pressure in the discharge system.

Backpressure is the sum of the superimposed and built-up backpressures. 


Or it is the sum of total variable backpressure (superimposed variable + built up) and constant backpressure.

Low NOX burners

Over 90% of the NOx from a typical flame is in the form of NO and the remainder is NO2.

NOX is controlled in a typical burner using

1. Staged fuel combustion
2. Fuel gas recirculation
3. Lean premix combustion
4. Air flow pattern

Good article here.

Is furnace arch / bridge wall temperature a function of fuel gas composition?

No. It is more of a function of air flow, coking of tubes, pass flows etc