Pilot High Low Pressure Sensorsensor - esp

The Axelson ESP Pressure Sensor is a highly accurate and reliable device designed to detect an abnormal operating condition in a safety system and transmitting a signal to perform a specific shutdown function. 

The Axelson ESP Pressure Sensor is a 3-way block and bleed valve that is controlled by a piston and spring.

It is used to sense predetermined pressure and, when that pressure is reached, shift the 3-way valve. 

The actuation point is easy to adjust by turning the adjustment cap. This changes the spring force. Turning the cap clockwise will increase the pressure setting. Turning the cap counter clockwise will decrease the pressure setting.

high or low pressure sensor  


The schematic illustrates a typical high-low safety shut-in system that uses an Axelson DG-3 diaphragm-operated gate valve, a pair of high-low sensors, and a PRV relay.


The sensor may be used to detect high pressure or a low-pressure conditions by connecting the input instrument pressure to the appropriate port. When connected to either port the remaining port becomes the exhaust port.

When used in a high pressure sensing application, the sensor allows flow through the instrument ports from "low" input to output as long as the sensing pressure increases to the high set point, the instrument input is blocked and the output is bled to the exhaust port.

When used in a low pressure sensing application, the sensor allows flow through the instrument ports from "low" input to output as long as the sensed pressure is above the low set pressure. When the sensing pressure decreases to the low set point, the instrument is blocked and the outlet is bled to the exhaust port.

Two Pilots can be connected in a series and used for both high and low sensing.  The combination high and low pilot is called the ESPHL.


  • Sensing pressure range from .5 to 20,000 psi

  • Instrument pressure range up to 200 psi

  • Block-and-bleed 3-way valve

  • Designed for 3% repeatability of set point, or 5 psi, whichever is greater.

  • Minimum spread (dead band) between trip and reset pressure

  • Spring maybe be replaced with instrument and sensing pressures present

  • Vent in lower housing provides warning if body is accidentally loosened from lower housing with sensing pressure present

  • Available to conform to NACE Standard MR-01-75

  • Corrosion resistant 316 stainless steel used throughout with Inconel spring optional.

  • Sensing pressure connections:
    9/16" HP on high-pressure sensors (20,000 psi)
    " NPT on low pressure sensors (diaphragm type)
    " NPT on all other sensors

  •  Metal-to-Metal seal between stem and body is designed to prevent flow line pressure or fluids from entering instrument pressure system if O-ring seal fails when sensor is in Fail-Safe Position

  • Vent acts as a warning allowing sensing pressure to bleed out prior to disengaging body from piston housing



sensor - esp


BASE NUMBER - 41046-XXX (Standard Body)   EXAMPLE:  41046-211 

High Flow Body - 41046-XXX3 (use 3 to indicate high flow)  Example: 41046-2113

Sensing Pressure Range Maximum W.P. Sensing Unit & Spring PART NUMBER
0.25 - 5.3 PSI 250 PSI 4" Diaphragm w/Ultra Light Spring ESP 41046-258
0.5 - 20 PSI 250 PSI 4" Diaphragm  w/Light Spring ESP 41046-218
1 - 40 PSI 250 PSI 4" Diaphragm w/Heavy spring ESP 41046-228
0.5 - 20 PSI 250 PSI 2" Diaphragm w/Ultra Light Spring ESP 41046-256
1 - 100 PSI 250 PSI 2" Diaphragm w/ Light Spring ESP 41046-216
2 - 200 PSI 250 PSI 2" Diaphragm w/ Heavy Spring ESP 41046-226
1 - 60 PSI 10,000 PSI 1-1/8" Piston w/Ultra Light spring ESP 41046-251
10 - 125 PSI 10,000 PSI 1-1/8" Piston w/Light spring ESP 41046-211
75 - 550 PSI 10,000 PSI 1-1/8" Piston w/Heavy spring ESP 41046-221
300 - 1,000 PSI 15,000 PSI 1/2" Piston w/Light Spring ESP 41046-212
500 - 2,000 PSI 15,000 PSI 1/2" Piston w/Heavy Spring ESP 41046-222
1,900 - 5,000 PSI 15,000 PSI 1/4" Piston w/Light Spring ESP 41046-213
4,900 - 10,000 PSI 15,000 PSI 1/4" Piston w/Heavy Spring ESP 41046-223
10,000 - 20,000 PSI 20,000 PSI 3/16" Piston with Heavy Spring ESP 41046-224


The ESP Sensor is also available with a high flow rate.  The High Flow Rate Body provides increased flow capacity and increased pressure capacity through the instrument ports. This allows the sensor to be used as a block and bleed valve with faster reaction times for the system.  It may also be used as a 2-way valve on a bleed only system.  

Instrument Pressure - 600 psi Maximum



Instrument Pressure Range
Standard Body .............   200 psi max.
High Flow Rate Body ...... 600 psi max.

NOTE:  When using a urethane o-ring on the stem - 1,480 psi maximum instrument pressure.

Repeatability to Set Point
within 3% of set point

Cv Factor (Flow Capacity)
Standard body ........  0.028
High Flow Rate Body ..... 0.058

Dead Band (Spread) .........................  Percent of Range
1 1/8, 1/2, 1/4 in. Pistons   ................  5%
Diaphragm Types ............................... 3%
3/16 in Piston .................................... 10%





axelson esp sensor



(1)  Cycle Test once a month or more often if service dictates.
(2)  Disassemble, inspect all parts, and replace O-rings annually or more often if service dictates.

ESPVITONKIT  -  Viton O-ring Kit
ESPBUNAKIT -    Buna O-ring Kit

Urethane O-ring needs to be specified and can be added to the kit.

(3) To change spring:  with flow line pressure at port D, loosed locknut and remove the cap.  Replace spring and reassembly.  (See spring part numbers below.)

Spring Part No:  (2nd Digit)

41047  -  Light-Steel Spring (Orange)
41048  -  Heavy-Steel Spring (Blue)
41049  -  Light-Inconel Spring (Yellow)
41050  -  Heavy- Inconel Spring (Green)
46301  -  Ultra-Light-Steel Spring  (White) 


axelson pressure sensor

P.C. McKenzie Company
P.O. Box 112638
Pittsburgh, PA 15241
Fax: 412-257-8890
Phone: 412-257-8866
P.C. McKenzie Company
1365 McLaughlin Run Road
Pittsburgh, PA 15241

Axelson ESP Pressure Sensor ~  Pressure Sensors