关于tescom regulator 的一些常见问题解答

What is droop?
This is the outlet pressure change (offset) from the SET (static) pressure which occurs as a flow rate increases.

When to use a tied diaphragm regulator?
The tied diaphragm design has a mechanical connection between the diaphragm and the valve stem. This is accomplished by welding a stud to the diaphragm and threading the valve stem into the stud tying the diaphragm to the valve stem. The tied diaphragm design controls the valve stem in both directions. The benefit of the tied diaphragm design is that if the regulator begins to creep, the increasing outlet pressure causes the diaphragm to flex upward away from the orifice pulling the valve stem tighter and tighter into the seat. The more outlet pressure drift or creep, the more sealing force is created. The sealing force will try to compress the contamination into the seat. Another name for the tied diaphragm design is a positive seal regulator.

What are Applications for a Tied Diaphragm Regulator?
The most common use for a regulator with the tied diaphragm design is regulating a toxic, corrosive or pyrophoric gas from a high cylinder gas pressure (above 500 PSIG) to a lower working pressure. In this application, if the regulator begins to creep, the tied diaphragm feature will protect the diaphragm from rupturing as well as components in the system downstream of the regulator.

What is an ER3000?

• An electropneumatic device
• A PID controller
• A low pressure, low flow, pressure reducing regulator
• The pilot to your regulator/valve

What is an electropneumatic device?
The user inputs an electronic signal, the device gives a pneumatic output.

What are PIDs?
P=proportional, I=integral, D=derivative PID is one of the oldest controls algorithm, which is commonly used in different industries.

What do you absolutely have to have to run an ER3000?

• 24 VDC power supply
• Pneumatic supply (up to 120 psig)
• A setpoint signal
• A feedback signal

Can you operate an ER3000 without a computer?
Yes. The computer MAY be used to send the setpoint signal (digital), but there are other options (analog signal, profile already on board the ER, or the UI3000).

Can you tune the ER3000 without a computer?
No, unless UI3000 is used.

What is "tuning"?
Tuning is the selection of the proper values for your P, I, and D gains so that the system gives you the optimal performance characteristics that include speed, stability, and agility.

Do you have to tune the ER3000 periodically?
No. Once the ER3000 is tuned for a system in the setup phase, there is no need to re-tune the system, unless the system's conditions and characteristics change so severely that the existing P,I,D values do not deliver the performance goals anymore.

How does ER3000 communicate with a computer?
RS485 communication

What is an A/D and its resolution in the ER3000?
An analog to digital converter and the resolution is 12 bits.

Can one use a digital transducer for feedback to the ER?
No, unless it is converted to an analog signal using a D/A.

What kind of analog signals can I send to the ER3000?
4-20 mA or 1-5 VDC for both setpoint and/or feedback (ER3000XI-X) 0-10 VDC for both setpoint and feedback (ER3000XV-X)

What kind of overall accuracy can I expect from a system with ER3000?
0.1% of the range of the transducer if the transducer has a 0.1% accuracy or better. Otherwise as accurate as the transducer.

What does an ER3000 do for my system?
Automation

• Send a setpoint to the ER, the ER will take you there.
• The ER automatically compensates for the changes in the system.
• No operator needed in the system once the setpoint is sent.
• Easy downloadable profiles eliminate PC or PLC for cycling applications.

• Closed loop control.
• Every 25 msec the ER looks at the setpoint and feedback and goes through the PID loop.
• User configurable PID parameters.

• Use Labview, Visual Basic, C.
• Use ER3000's software package.
• Data collection.
• monitoring using a PC.

What does 1 "bit" in the system amount to (w.r.t. pressure or other control variable)?
1 bit is equal to 0.03% of the sensor's range (the sensor that is used for feedback). You can never do better than 1 bit.

Can you collect data with an ER3000, w/o a computer?
No.

Can you collect data with a combination of ER3000/UI3000, w/o a computer?
No.

Do you lose your PID parameters on the ER when power is lost (or ER is unplugged)?
No.

Do you lose communication with the PC in case of a power loss?
Yes.

Do you lose your communication with the PC, if you are sending an analog setpoint to the ER?
No.

What happens to pressure when power is lost?
For the first 250 msec, the ER goes into the failsafe mode. After that since the solenoid valves in the ER are normally closed, the valves will close and the pressure is either trapped (in case the ER3000 is mounted into a dead headed system e.g. dome of a regulator) or the pressure would be lost if the ER is in flowing conditions.

What does "failsafe" mean in the ER3000?
The user may configure the ER (using the computer, or UI3000) so that the system is driven into the failsafe mode if one or more of the following 5 parameters fall below or go beyond their min and max values. Notice that the user has the option of changing these min and max values, or disabling that parameter(s) so that regardless of its value the unit does not go into the failsafe mode. The 5 parameters are: analog setpoint, internal sensor, external sensor, inner error, and outer error. The failsafe mode can also be configured by the user to be one of the following 4 conditions: inlet closed/exhaust open, inlet closed/exhaust closed, inlet open,/exhaust open, inlet open/exhaust closed. Once the ER is in the failsafe mode, the PID controller is disabled and the mode stays on until the parameter that caused the condition falls back into its "working" range.

What happens when you lose your analog setpoint source?
If a failsafe range has already been established, once the setpoint goes below its minimum, the ER will go into the failsafe mode (the valves will be open or closed depending on the user selection). If failsafe is disabled for the analog setpoint, then losing the setpoint will be translated into asking for 0 setpoint. The ER will open the exhaust valve, and the pressure is lost.

What happens if the feedback signal is lost?
If a failsafe range has already been established, once the feedback goes below its minimum, the ER will go into the failsafe mode (the valves will be open or closed depending on the user selection). If failsafe is disabled for the feedback, then losing the feedback will be translated into having 0 feedback. The ER will open the inlet valve to bring the feedback up to the setpoint value (if the setpoint is not zero) but obviously the feedback will not change. So the ER will stay full open.

What happens if the pneumatic signal is lost (0-120 psig into the ER)?
The pressure is eventually lost if either solenoid valves open.

What happens if the communications with PC is lost?
It depends:

• If the PC was sending a constant setpoint to the unit, the unit will continue on with the last setpoint it received and tries to hold the feedback at that level (no major change).
• If the PC was sending a varying setpoint to the ER, the ER will take the very last setpoint (before comm was lost) and holds that as the setpoint.
• If the PC had already downloaded the profile into the ER and started the profile, the profile will continue without interruptions if communications is lost.
• If an analog setpoint was being sent to the ER, the ER3000 will not be affected by the loss in communications.

Can the user adjust the PID parameters on the board using pots or jumpers?
No.

What are the things I can do with the boards to setup the system?
Proper jumper position to select between current and voltage setpoint and feedback. You may also use the zero and span push buttons to calibrate the system, but this can be done (more easily) through the software.

How durable are the solenoid valves?
Clippard (the manufacturer of our valves) cycled them over 100,000,000 times. They stopped not because the valve failed, but because they got tired of running it.

What is the Cv of the solenoid valves?
0.01.

Can I use the ER3000 for High Purity applications?
Yes, you will need to couple it with a high purity regulator/transducer.

Can I use it for hydraulic applications?
Yes, you will need to couple it with a hydraulic regulator/transducer.

What is the maximum flow and pressure that I can use the ER for?
As high of a flow and pressure that your mechanical regulator is capable of delivering. If the ER3000 is used as a standalone unit, it is a pressure reducing regulator with the following characteristics: P1(max)=120 psig, P2(max)=100 psig, Cv=0.01, media compatibility: dry clean air, N2, Argon, loading mechanism: analog or digital setpoint, closed loop system

Can I use the ER with a back pressure regulator?
Yes. The transducer needs to be on the inlet side of the regulator in this case.

Can I use the ER3000 in vacuum service?
Yes:

• If the ER3000 is used as a standalone, connect the vacuum pump to its exhaust port, put the absolute transducer on the outlet of the ER, and operate in the external feedback mode. The inlet may be open to atmosphere, or you may apply up to 120 psig, depending on availability of your supply and the flow needed in the system.
• If the ER3000 is used with a vacuum service regulator (44-4600, 44-4700, 44-5000, FR, DV) then the ER3000 will act as the pilot to the regulator.

Accumulation Pressure - The increase in the inlet pressure to a back pressure regulator required to obtain a specified flow rate.

Accuracy - The variation in outlet pressure which occurs under steady state conditions within the control range of a regulator.

Balanced Valve - A main valve which has been designed to be pressure balanced, hence, the main valve spring provides the shut-off force. The three major benefits of the balanced valve design are: (1) a reduced seat load, (2) larger seat orifice capability (larger flows), and (3) reduced decaying inlet characteristics.

Bellows - One of three styles of sensing elements. It is the most accurate of the three sensing elements. The sensitivity is due to its large sensing area and many flexing points.

Bias - The pressure increment which is adjusted or preset into a regulator and is usually held constant during normal functioning.

Burst Pressure - A design test pressure which determines the ultimate structural strength of a regulator or valve. Permanent deformation and leakage are permitted, but parts must remain assembled (no sudden ruptures). Accepted industry standard per ANSI/ASTM B31.3.

Captured Venting - A feature incorporated in a self-venting pressure reducing regulator which provides an additional port to permit the piping away of the expelled fluids from the regulator's vent valve.

Control Element - One of the three basic elements of a pressure regulator. It acts to reduce a high inlet pressure to a lower working or outlet pressure. The control element sometimes called a main valve, valve stem, or poppet.

Cracking Pressure - A term used in back pressure control only and is the inlet pressure, to the regulator, at which flow starts.

Creep - Any increase in the outlet pressure subsequent to lock-up, usually a long-term slow pressure increase. This indicates a regulator leak and calls for the immediate removal of the regulator for service.

Cv - See "Flow Capacity".

Decaying Inlet Characteristic - The effect on the set pressure of a regulator as a result of an inlet pressure change; normally an increase in outlet pressure due to a decrease in inlet pressure.

Diaphragm - One of several types of sensing elements. The diaphragm style is very sensitive in reacting to outlet pressure changes. Slightly less so when the diaphragm is metal. Common diaphragm materials are Buna-N, Viton, Ethylene Propylene, 316 Stainless Steel, and Elgiloy.

Differential Pressure Regulator - A pressure control regulator which is designed to provide a controlled pressure which is the sum of a signal (reference) pressure and a bias pressure. The bias may be either positive or negative.

Dome Loading - One type of loading element. Gas or liquid is put into the dome of a dome regulator at a pressure equal to the outlet pressure desired. This dome pressure is normally provided by a second regulator called the pilot regulator.

Droop - The outlet pressure change (offset) from the "set pressure" which occurs as flow rate increases.

Flow Capacity (Cv) - The maximum flow capability of a regulator or valve established at a specific set of conditions. The standard coefficient is the term Cv which by definition is the flow of one GPM of water at one PSI drop. The term Cv for gaseous service is dependent on the ratio of inlet to outlet pressure and must be determined by the use of appropriate formulae.

Flow Rate (Q) - The quantity of fluid being passed through a regulator or valve during a specified time period. Units of measure include: SCFM, SCFH, L/Mn, GPM, and GPH.

HPIC - High purity internal connection (internal female VCR)

Inlet Pressure (P₁₎ - The pressure of the fluid media, gas, or liquid, to the supply connection of a regulator or valve. Typical units of measure are: PSIG, BAR, or PASCAL.

Leakage - External - The loss of fluid from the external surfaces or joints of a regulator or valve. Example: From the body-bonnet-diaphragm joint.

Leakage - Internal - The loss of fluid through a regulator or valve, between pressure zones normally expected to be sealed. Example: Between the inlet pressure (P1) and the outlet pressure (P2) zones.

Leakage - Inboard - Leakage through an external joint or seal where the direction of flow is from the outside into the regulator or valve. The leakage rate is measured in atm cc/sec He(lium).

Leakage - Outboard - Leakage through an external joint or seal where the direction of flow is from the inside of the regulator or valve to the outside. The leakage rate is measured in atm cc/sec He(lium) and the pressure inside the regulator should be stated.

Load Element - One of the three basic elements of a pressure reducing regulator. It provides the means by which the operator can set the force that determines the outlet pressure of a regulator.

Lock-Up - The outlet pressure increase which occurs above the "set pressure" as the flow is decreased to zero.

Minimum Controllable Flow - The lowest volume of fluid, gas, or liquid, a regulator can pass and still maintain steady state conditions.

Minimum Controllable Pressure - The lowest pressure which a regulator can control and still maintain satisfactory performance.

Outlet Pressure (P₂) - The pressure of the fluid media, gas, or liquid, from the discharge connection of a regulator or valve.

P₁ - See "Inlet Pressure."

P₂ - See "Outlet Pressure."

Pilot Regulator - A pressure reducing regulator which feed gas or hydraulic pressure into the dome of a dome loaded regulator. The pilot regulator should be a venting type regulator in order to permit pressure in the dome to be adjusted to a lower pressure.

Piston - One type of sensing element. A very strong unit made of brass, 303, or 316 Stainless Steel and used in high pressure applications up to 15,000 PSIG.

Proof Pressure - A test pressure which is applied to all pressure zones of a pressure regulator or valve to verify structural integrity. No deformation or excessive leakage is permitted at this pressure. The regulator or valve must function normally after this test. The accepted industry standard is 1.5 times (150%) the rated working pressure.

psia (absolute pressure) - A measure of pressure in psi that is referenced to zero absolute pressure.

psig (gauge pressure) - A measure of pressure in psi that is referenced to ambient pressure.

Q - See "Flow Rate."

RA finish - Roughness average. Tescom machines to a roughness average which does not exceed 10 RA.

Repeatability - The ability of a regulator to return to the same set pressure subsequent to being subjected to various flow demands.

Reseat Pressure - The inlet pressure of a back pressure regulator at which flow stops.

Self-Venting - A feature incorporated in certain pressure reducing regulator which enables the unit to vent the outlet (downstream) pressure when the handknob is adjusted in the decrease direction (counterclockwise).

Sensing Element - One of the three basic elements of a pressure reducing regulator. It senses the changes in the outlet pressure permitting the regulator to react and attempt to return to the original "set pressure" by increasing or decreasing pressure.

Sensitivity - The ability of a pressure regulator to respond to change in discharge conditions: pressure, flow, temperature, etc.

Set Pressure - The desired operational outlet pressure for a regulator, normally stated at NO FLOW conditions.

Set-Ability - The minimum pressure increment or fraction thereof, which can be achieved by an experienced operator, when setting a pressure regulator.

Specific Gravity (Sg) - Specific gravity of gases is the ratio of molecular weight of any gas to that of air.

Specific Gravity (SL) - Specific gravity of liquids is the ratio of specific weight of any liquid to that of water.

Unbalanced Main Valve - The most common main valve design. Inlet pressure provides the majority of the shut-off force. The function of the main valve is to reduce the high inlet pressure to a lower outlet pressure.