Murphy PXT Series User manual

Description
The PXT Series pressure transmitters are state-of-the-art instruments providing 4 to
20 mA outputs. They feature a precision micro-machined silicon diaphragm with
fully welded stainless steel pressure port for greater accuracy, stability and a wide
range of compatibility. All wetted parts are 316L stainless steel or Hasteloy C276.
Specifications
Accuracy (Full Scale, Best Straight Line): ±0.25% including non-linearity,
hysteresis and repeatability. Long term stability better than 0.2% FS over
twelve (12) months.
Zero Setting: ±0.5% of full scale (0.25% typical).
Span Setting: ±0.5% of full scale BSL (RSS).
Overpressure/Proof Pressure: 400% for up to 500 psi (3.45 MPa)
[34 Bar]. 200% for higher ranges.
Burst Pressure:
Ranges 0-1000 psi = 600% of full scale or 4000 psi whichever is lower.
Ranges 2000 psi 13.79 MPa) [137 Bar]= 20,000 psi (27.5 MPa) [275 Bar].
Response Time: Frequency response better than 2 kHz.
Storage Temperature: -65 to 200°F (-54 to 93°C).
Operating Temperature: -40 to 180°F (-40 to 82°C).
Compensated Temperature: -20 to 160°F (-29 to 71°C).
Total Thermal Effects Over Compensated Range: ±2% FS TEB.
Physical:
Enclosure: Weather Resistant.
Body: 316 stainless steel. Meets NACE MR01-75.
Wetted Parts: 316L stainless steel or HASTELLOY C276.
Process Connection: 1/4 NPT female.
Electrical Cable: Integral; 60 in. (914 mm); vented.
1/2 in. NPT male conduit connection
Environmental Effect:
Humidity: No effect.
Mounting: Position/orientation has negligible effect.
Reverse polarity protected
Shock: 1000g 1ms Half sine Pulse in each of 3 mutually perpendicular axis
will not affect performance.
Vibration: Effect on output response is less than 0.05% FS/g at 30g Peak
10Hz to 2kHz, limited by 0.05 in double amplitude. (MIL STD 810C
Proc. 514.2-2 curve L).
PXT Power Requirements: Typically 24 VDC is required, using the Loop
Resistance Graph, 9-30 VDC.
PXT Series Transmitter Output: 4–20 mA, 2-wire.
Insulation: Greater than 10 Mohms @ 500 VDC.
RFI Protection: To the European standards of BS EN 50082-2:1991 in
accordance with IEC 801 parts 1 to 6 for suspectibility to EMC and to
BS EN 50081-1992 for emissions.
Voltage Surge/Spike: Protected against a 600 V spike to IEC 60-2. Reverse
polarity protected.
Sealed: Sealed at one atmosphere at sea level for ranges > 1000 psi (6.89
MPa) [68 Bar].
Vented: Vented for ranges < = 1000 psi (6.89 MPa) [68 Bar].
Laboratory Approvals: UL/CUL Class I, Div. 1, Groups A, B, C, D. Class II,
Division 1, Groups E, F, G; when installed with approved barrier per draw-
ing 05-08-0754 UL/cUL Class I, Div. 2, Groups A, B, C, D. Class II
Groups E, F, G, non-incendive per drawing 05-08-0754.
Ranges Available
†
PXT Series Pressure Transmitters
Installation Instructions
00-02-0475
Revised 2012-05-04
Section 05
Please read the following information before installing.
A visual inspection of this product for damage during shipping is recommended before mounting.
WARNING
This Murphy instrument is susceptible to damage when exposed to
static electrical charges. To avoid damage, observe the following:
✔✔Ground transmitter body before making electrical connections.
✔✔When disconnecting, remove ground connection last.
✔✔Disconnect all electrical power to the machine.
✔✔Make sure the machine cannot operate during installation.
✔✔Follow all safety warnings of the machine manufacturer.
✔✔Read and follow all installation instructions.
Loop Resistance Graph
Supply voltage for the PXT must be within range of 9-30 VDC. The Graph below
shows the minimum supply voltage (VDC) required for a given load resistance (RL).
1500
1000
500
2 50
10 2 0 3 0 4 0 501 4 V @
2 50 ohm
0
Total Load Resistance (RL)*
(OHMS)
Power Supply Voltage (VDC)
*NOTE: Cable resistance effect included in RL.
19V, 500 Ω
29V, 1000 Ω
Under
Voltage
Area
Operating
Area
Over
Voltage
Area
RR
Listed for Class I,
Div. 2, Groups A, B, C, D
and Div. I, Grps. A, B, C, D with a Barrier
Pressure Range†:
Specify For this range
30V30WC -30” H20 to +30” H20 (-76 cm H20 to +76 cm H20) [+/-0.075 Bar]
30V30 -30” Hg to +30 psig (-76 cm Hg to 207 kPa) [2.07 Bar]
30V100 -30” Hg to +100 psig (-76 cm Hg to 689 kPa) [6.89 Bar]
15 0-15 psi (103.4 kPa) [1.03 Bar]
60 0-60 psi (413.7 kPa) [4.13 Bar]
100 0-100 psi (689 kPa) [6.89 Bar]
200 0-200 psi (1.38 kPa) [13.78 Bar]
300 0-300 psi (2.07 kPa) [20.67 Bar]
400 0-400 psi (2.75 MPa) [27.56 Bar]
600 0-600 psi (4.14 kPa) [41.34 Bar]
1000 0-1,000 psi (6.89 MPa) [68.9 Bar]
2000 0-2,000 psi (13.79 MPa) [137.8 Bar]
3000 0-3,000 psi (20.69 MPa) [206.7 Bar]
5000 0-5,000 psi (34.48 MPa) [344.5 Bar]
6000 0-6,000 psi (41.37 MPa) [413.4 Bar]
†
NOTE: Conversions are approximate.
Installation 00-02-0475 page 1 of 2

WARNING: READ BEFORE INSTALLATION
Fluid hammer and surges can destroy any pressure transmitter/transducer
and must always be avoided. A pressure snubber should be installed to
eliminate the damaging hammer effects.
Fluid hammer occurs when a liquid flow is suddenly stopped, as with
quick closing solenoid valves. Surges occur when flow is suddenly begun,
as when a pump is turned on at full power or a valve is quickly opened.
Liquid surges are particularly damaging to pressure transmitter/trans-
ducer if the pipe is originally empty. To avoid damaging surges, fluid
line should remain full (if possible), pumps should be brought up to
power slowly and valves operated slowly. To avoid damage from both
fluid hammer and surges, a surge chamber should be installed, and a
pressure snubber, such as Murphy PD-8100 Series (adjustable) or
PM6203 Series (fixed) call Murphy for details, should be installed on
every transmitter/transducer.
Symptoms of fluid hammer and surges damaging effects:
a. Pressure transmitter exhibits an output at zero pressure (large zero offset).
b. Pressure transmitter output remains constant regardless of pressure.
c. In severe cases, there will be no output.
Noise
For minimum noise susceptibility avoid running the transmitters/transduc-
ers cable in a conduit that contains high current AC power cables or igni-
tion loom on engine. Where possible avoid running the cable near induc-
tive equipment. Shielded cable is always recommended. Earth the shield
at one end only.
Mounting
CAUTION: THESE ARE PRECISION INSTRUMENTS.
DO NOT INSTALL IN ANY MANNER THAT CAN CAUSE
SIDE STRESS OR IS SUBJECT TO EXCESSIVE VIBRATION.
The transmitter/transducer requires no special mounting hardware and
can be mounted in any plane with negligible position error.
Although the unit can withstand substantial vibration without damage
or significant output effects, it is always good practice to mount the
transmitter where there is minimum vibration.
Apply Teflon tape/sealant to the pressure fittings threads before
installing. When tightening, apply a wrench to the hex wrench flats
located just above the pressure fitting. DO NOT tighten by using a
pipe wrench on the housing.
PXT Series Electrical Connections
Hold when attaching
to pressure source
Do NOT twist body
1/4 NPTF
2.08 in.
(53 mm)
7/8 Hex 316 Stainless
Steel Housing
2 in.
(51 mm)
2.30 in.
(58 mm)
2.30 in.
(58 mm)
.86 in.
(22 mm)
.866 A/F
1/2 NPTM
7/8 Hex 316 Stainless
Steel Housing
60 in. (1524 mm)
long cable-std.
.86 in.
(22 mm)
1.18 in. Dia.
(30 mm)
1/4 NPTF
1.18 in. Dia.
(30 mm)
.866 A/F
1/2 NPTM
60 in. (1524 mm)
long cable-std.
High Pressure Units
Isc 93 mA
La
Ca 0.12 F
3 mH
POWER BARRIER
Voc 28 V
USE THE FOLLOWING PARAMETERS IF CABLE
PARAMETERS ARE UNKNOWN.
CABLE CAPACITANCE: 60 pF/ft
µF)
HAZARDOUS AREA SAFE AREA
Class I, Groups A, B, C, D
Class II, Groups E, F, G
PXT SERIES
ALL INTRINSICALLY SAFE WIRING SHALL BE KEPT
SEPARATE FROM NON-INTRINSICALLY SAFE WIRING.
REFER TO ARTICLE 504 OF THE NATIONAL
ELECTRICAL CODE OR THE CANADIAN ELECTRICAL CODE.
TRANSMITTER ENTITY PARAMETERS
TERMINALS VMAX IMAX CI LI
POS - NEG 28 V 93 mA 0.11 F O.22 mH
BUSBAR
OUTPUT CURRENT MUST BE LIMITED BY A
RESISTOR SUCH THAT THE OUTPUT VOLTAGE
Vs CURRENT PLOT IS A STRAIGHT LINE
BETWEEN Voc AND Isc
BARRIER MUST BE INSTALLED AS
INSTRUCTED BY THE MANUFACTURER
SELECTED BARRIER INTRINSICALLY SAFE
CIRCUITS SHALL BE APPROVED FOR
CLASS I, II, III DIV 1 & 2, GROUPS A-G
TERMINATE BARRIER EARTH GROUND TO THE
GROUND BUS OF THE POWER DISTRIBUTION
PANEL. RESISTANCE TO GROUND MUST NOT
BE GREATER THAN 1 OHM
1
2
3
4
BARRIER NOTES
CONTROL EQUIPMENT
MUST NOT BE CONNECTED TO
EQUIPMENT WHICH USES OR
GENERATES MORE THAN
250 VRMS WITH RESPECT TO
EARTH GROUND
POWER
RETURN
V SUPPLY
EARTH GND
Vmax >= Voc
I max >= Isc
Ci + C cable =< Ca
Li + L cable =< La
CABLE INDUCTANCE: 0.2 µH/ft
(EX.L Cable=1000ft x 0.2 µH/ft=0.2mH)
INSTALLATION INSTRUCTIONS FOR CLASS I DIV 2
UNITS MEET CLASS I DIV 2 WHEN INSTALLED IN ACCORDANCE
WITH CLASS I DIV 2 METHODS. EITHER BY USING THE CONDUIT
AND GROUND CONNECTION PROVIDED OR BY INSTALLING IN A
SUITABLE ENCLOSURE ACCEPTABLE TO THE LOCAL AUTHORITY
HAVING JURISDICTION.
INSTALLATION INSTRUCTIONS FOR CLASS I DIV 1
µ
F
F
µ
FF