It’s frustrating when you buy a high accuracy pressure transducers or transmitter like the U5100 series by Measurement Specialties and the delivered part does not work as advertised. The advertised typical accuracy specification for this device is better than .25%FS, but the reading that you are seeing is more in the order of 1%FS. Chances are that the sensor is actually working fine, and the problem is that the device is simply not vented properly. This is typically found to be true when a Bendix style bayonet connector is used.
Bayonet style connectors are the best style connectors used when connecting to pressure sensors. The locking mechanisms will prevent the device from shaking loose, and the o-ring with-in the connectors assure an IP64 (ingress from water spray) protection. While not a hermetic seal, the connection is pretty close.
This is great for most applications. However, for pressure transducers and transmitters in pressure range less than 1000 psi, the device must be vented to the atmosphere. Just connecting any mating connector to the device will turn a vented gauge device into a poorly made type of sealed gauge device. That is, when the mating connector is attached, some air is sealed within the connector and no ventilation to the atmosphere occurs. At room temperature it will appear that the offset has shifted, and over temperature you will be governed by Boyle-Mariotte law (PV=nRT). This is easily corrected.
When the pressure transducers are made, the vendors take special care in the manufacturing process to be sure the devices are vented. If you ask the manufacturer you will be told that the connector is custom-made for the pressure transducer. In the case of the US10,000 the device was made with a customer connector in that pin F was removed. I guess this is true, the connector was custom-made, but what has actually happen is that the Meas-Spec has used needle nose pliers and removed the unused pin, F within the connector. The mating connector added by the user must have the vent hole in the same place, Pin F, to function properly. The nice people at Measurement Specialties will sell you the correctly “made” mating connector, at an additional price, but you can make this connector yourself by pulling out the pin on your connector with needle nose pliers as well. This will correct the problem